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CHEMISTRY NOTES

DEFINITIONS

Atom: the basic unit of a chemical element. Element: each of more than one hundred substances that cannot be chemically broken down into simpler substances and are primary constituents of matter. Each element is distinguished by its atomic number, i.e. the number of protons in the nuclei of its atoms. Molecule: the smallest unit of a substance, which retains all the physical and chemical properties of that substance. Ex., one molecule of water: H2O Compound: A substance containing two or more elements chemically combined. Example: NaCl2 H2O Mixture: Two or more elements or compounds which are bonded without combining chemically.

Solutions Solutions are homogeneous mixtures Soluble: able to dissolve Insoluble: unable to dissolve. Example: Soluble: salt water Particles in solutions are too small to see because they never settle out Concentration can be measured in grams. Solubility is expressed in grams.

Suspensions Suspensions are heterogeneous mixtures Example: dirty air Particles in suspensions are large Suspensions can be separated by passing through a filter

Colloids Particles in colloids are small and well mixed Example: gelatin and whipped cream Particles in colloids are smaller than particles in a suspension Colloids are small enough to pass through a filter

Ion: A charged particle formed from an atom or atoms that have gained or lost one or more electrons. A positive ion loses electrons. A negative ion gains electrons. Example: NaCllll in water solution becomes Na+ and Cllll

-

Catalysts Substances that speed up a chemical reaction but they do not take part in the reaction.

Isotopes - atoms of the same elements that have the same number of protons but different number of

neutrons. Example: C-12; C-14.

Covalent Bond: Bond between atoms produced by sharing of electrons.

Ionic Bond: A type of bond in which ions are held together by the strong attraction of their opposite charges.

PHASES (States) of MATTER

All matter exists as a solid, liquid, or a gas. There is a 4th state called plasma but it is only found in space.

SOLID: has a definite shape and volume. The particles a solid is made of are closely packed together and there is little and slow movement. Ex., rock

• When the particles making up the solids are arranged in a regular, repeating pattern, they are called crystal.

• When particles making up the solids are not arranged in a regular, repeating pattern, and they don't keep their definite shapes permanently are called amorphous solids. Example: sealing wax, silicone rubber, candle wax, window glass, tar.

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LIQUID: has definite volume but not definite shape. It takes the shape of its container. Its particles move faster than the particles of solids and they can roll over and around one another so they pour, and flow. Example: Water

• Some liquids flow more easily than others.

• The resistance of a liquid to flow is called viscosity. (viscosity of honey is greater than water). GAS: has no definite shape, no definite volume. Particles are not closely packed. They move at high speeds (1500 km/h) and expand to fill all space available in the container. If there was no gravity, gases would keep spreading. Example: Steam PLASMA: The 4th phase of matter, exists only at very high temperatures (5800 K), for ex. the surface of the sun is in the plasma state. It has some of the properties of a gas but it consists of electrically charged particles. It is nuclear produced energy that can be converted to electricity. Can only be contained in magnetic fields, and it's dangerous to living things. Example: Energy in the sun

PROPERTIES OF GASES Diffusion: The tendency of particles of matter to move away from where they are close together, and to mix with other particles. Occurs in gases, liquids, and solids. THINK of examples of diffusion. Boyle's Law: (Robert Boyle) the volume of a gas decreases when its pressure is increased if the temperature is constant (doesn't change). Particles of a gas are pushed closer when the pressure is increased. Thus, the volume decreases. Example: Opening a bottle of soda pop (reduce pressure, gas expands). Charles' Law: (Jacques Charles) The volume of a gas increases when its Kelvin temperature is increased, if the pressure is to remain the same. (0 K is the point at which particle motion is at a minimum). All gases become liquids or solids before they are cooled to this temperature. • Heating a gas causes it to expand.

• Gas particles gain kinetic energy by an increase in temperature.

• The particles move faster and strike the walls of the container more often.

• If the walls of the container are flexible, the gas pushes them out. • There is an increase in volume. ACTIVITY: Blow up a round balloon. Measure its circumference and record. Place it in hot water for 10 min. and measure. Then place in ice water for 10 min., measure again. Write a short lab report by following the scientific method steps, and explain what happens in terms of Charles' law.

CLASSIFICATION OF MATTER

Matter is classified into 2 classes: 1) Substances (composition definite); a) elements: Ex., H, O, Ca, Na, etc., b) compounds: Ex., H2O, HCl, l, l, l, etc. 2) Mixtures: a) Homogeneous mixtures (solutions): Ex., Air, lemonade,

tea with honey, salt water, etc. b) Heterogeneous mixtures: Ex., salad, taco, soup, etc. Mixtures Is lemonade a mixture? What type? H2O (water) (Dihydrogen Oxide) Sugar (Diglycerides) Lemon juice (Citric Acid) LEMONADE is a homogeneous mixture.

• The substances that make up lemonade are all mixed together and you can taste the lemon, the sugar, and the water in your mouth.

• All the substances together make the taste of lemonade.

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If there were a lemonade molecule, then you would not taste the different substances that make up lemonade

AIR--What is air? Air is a mixture of gases. A homogeneous mixture.

ATOM MODEL

Rutherford and Bohr Model Electrical Nature of Matter

• there are two kinds of electric charges: 1) Positive (+), 2) Negative (-).

• attraction = + and - (unlike charges)

• repulsion = + & + or - & - (like charges)

• electron has - charge

• proton has +ve charge • neutron has no charge

• electrons are found in the electron cloud around the nucleus

• protons and neutrons are found in the nucleus • the mass of a neutron = mass of a proton

• the mass of a proton is 1,840 X the mass of an electron

• protons keep neutrons stable • a neutron will decay into a p+ and an e- if it's alone without a proton

• the overall charge of an atom is neutral because it has equal number of protons and electrons and cancel each other's charge out

Na energy level, shell, or orbital ------>

Energy level or orbital: the electrons are arranged on energy levels and orbit the nucleus. Electron cloud: the area around the nucleus where the electrons are found. Forces of the atom---What keeps the subatomic particles together? The atom is comprised of three major particles--protons, neutrons and electrons. There are four forces: Electromagnetic, Strong, Weak, and Gravity, that are responsible for the behavior of the particles and thus keep the atom together. Electrons are kept in the orbit around the nucleus by the electromagnetic force, because the nucleus in the center of the atom is positively charged and attracts the negatively charged electrons. The strong force opposes the repulsive charges of the protons and keeps them together in the nucleus, like glue. The weak force keeps the neutrons stable and prevents them from decaying radioactively to protons and electrons. Gravity is very small in the atom but it is present in every object with mass and it is the force of attraction between objects.

11p 12n

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PERIODIC TABLE

Each box (see below) on the periodic table contains information for each of the element. The full name of the element, the chemical symbol, the atomic number (smaller of the two numbers), and the atomic mass or weight (bigger number of the two). The chemical symbols of the majority of the elements derive from the Greek and the Latin languages. The color indicates the physical state of the element under ordinary conditions.

---------------Atomic number --------------- Chemical Symbol --------------- Atomic Weight (atomic mass) (rounded off to the nearest whole number)

------------- Name of element

# of protons (p) = # of electrons (e-) = atomic number # of neutrons (n) = atomic mass - atomic number

nucleus = n + p = 108 n = 108 - 47 n = 61 The elements on the Periodic Table are arranged in order of their increasing atomic weight (mass). The atomic number of an element determines the chemical properties of an element. atomic # = number of protons = number of e-s. Chemical properties of elements are related to the arrangement of electrons in the atom. Atomic Weight is the weight of 6 x 1023 atoms of the element in grams. For example: 6 x 1023 atoms of the element carbon weighs about 12 a.m.u. Oxygen = 16 a.m.u. The Periodic Table is made of Columns or Groups or Families. They contain elements with similar chemical properties. Ex.1) VIIA The Halogens: fluorine; Chlorine; Bromine; Iodine; Astatine. All have 7 electrons in their outer energy level. Therefore, they react similarly.

Ex. 2) VIIIA Noble Gas Family: All noble gases have 8 electrons in their outer energy level, except Helium (He) which has

2. Noble gases don't react with other elements under normal circumstances.

Periods of Elements

The Rows on the periodic table are called periods. Elements in periods have different properties. Elements on the LEFT side are METAL. A Metal atom has 3 or fewer electrons in the outer energy level. Cu; Fe; Zn; are metals. Properties: Good conductors of heat and electricity. ALKALI METALS: Lithium; Sodium; Potassium; Rubidium; Cesium; & Francium.

• soft, shiny, reflect light, malleable, and ductile.

• very reactive (never found as free elements).

• to identify the alkali metals we do the flame test.

• when ions or vapors of these elements are heated in a flame, some of their electrons gain energy. These electrons move to higher energy levels. As they return to their previous state, these electrons lose this energy in the form of light.

How do alkali metals form compounds? By ionic bonding. ALKALINE EARTH METALS: Beryllium; Magnesium; Calcium; Barium; radium. USES: Beryllium - the mineral beryl Magnesium - photographic flashbulbs Calcium - Plasterboard Barium - study digestive tract Radium - to treat cancer

47 Ag 108 Silver

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TRANSITION ELEMENTS: Metals with at least two electrons in their outer shell. The elements found in this group are very similar to the ones in the alkali and alkaline families.

NONMETALS

• 5 or more e-s in outer energy level. • poor conductors of heat and electricity. • stair-like line on periodic table divides the metals on the left with the nonmetals on the right.

METALLOIDS: have properties of both metals and nonmetals. Example: Boron; Si; Ge; As; Sb etc. COMPOUNDS: A compound is formed when two or more elements combine chemically. A compound is different than the elements made of. CO2 = 1 C atom and 2 O atoms "Combine Chemically" is when the elements join (bond) together in a way that makes it impossible to separate them by physical means. Chemical Formula is a way to represent compounds. It shows the kinds and number of atoms in a compound. Example: CO2 The 2 in CO2 is called subscript and represents 2 atoms of oxygen. C represents one atom of carbon. The ratio between C and O is 1:2.

ELECTRON CONFIGURATION

The s sublevel has just one orbital, so can contain 2 electrons max. The p sublevel has 3 orbitals, so can contain 6 electrons max. The d sublevel has 5 orbitals, so can contain 10 electrons max. The f sublevel has 7 orbitals, so can contain 14 electrons max. How do I read an electron configuration table? The total number of electrons in an energy level is the sum of the electrons in each sub-shell of that energy level. Just add the numbers in superscript together to find the number of electrons in an energy level. ?The number of electrons in each energy level in an atom of gold is shown below: 1s2 2=2 electrons in level 1 2s2 2p6 2+6 =8 electrons in level 2 3s2 3p6 3d10 2+6 = 10 = 18 electrons in level 3 4s2 4p6 4d10 4f14 2+6 +10 +14 = 32 electrons in level 4 5s2 5p6 5d10 2+6+10 =18 electrons in level 5 6s1 1=1 electron in level 6 (highest energy level of Au is 6) The maximum number of electrons that can occupy a specific energy level can be found using the following formula: electron capacity = 2n2 n= the number of energy levels.

Energy Level Electron Capacity 1 2 2 8 3 18 4 32 5 50 6 72

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ISOTOPES

• Isotopes are atoms of the same element with the same number of protons but different number of neutrons, thus different atomic weight (mass). Ex. C-12 and C-14.

• Hydrogen has 3 isotopes: Protium, Deuterium, Tritium.

• Isotopes are radioactive if their nuclei have too many or too few neutrons. • Most elements have radioactive isotopes.

• Rare for small atoms.

• The heaviest elements, the ones beyond bismuth (Bi) – all of the isotopes are radioactive.

• Radioactivity is measured with a device called a Geiger counter.

• Audible (can hear) clicks are heard when an atom changes. • More clicks indicate that more particles are being produced.

• Radioactivity is used in hospitals to diagnose and treat patients. Some forms of radiation can be used to destroy harmful tumors inside a person’s body

• Can also be used to test if the organs in the body are functioning properly

• Doctors can detect the radiation produced by the isotopes. • It is harmful to living things in large doses.

• Radioactivity can damage or kill cells.

• The energy from its particles can burn the skin

• Extended contact with radiation causes cancer and other health problems like infertility.

MOLE Mole (mol.) is a counting unit. One mole of water is 602,000,000,000,000,000,000,000 or (6.02x1023) water molecules.

• One mole of water is less than 1/10 of a cup which is equal to 18g or 18ml.

• If you string one mole of paper clips, the string will go around the earth 400 trillion (4x1014) times and it will take you 190 million centuries.

• 1 mol of C = 12.01g 1 mol of Cu = 63.55g

• The mass of one mole of an element’s atoms equals its atomic weight. Example: 1 mole of C x 12.01 g C = 12.01C

1 mol C Molar mass of Cu2CO3(OH)2 = 22.1g Cu2CO3(OH)2 Avogadro’s number 6.02 x 1023 particles, which represents one mole of particles. Avogadro’s Law Equal volumes of all gases, measured at the same temperature and pressure, contain the same

number of gas molecules.

PHYSICAL AND CHEMICAL CHANGES

Physical Properties: Traits or characteristics. What something looks like. For example: color, shape, density, phase (solid, liquid, gas). Chemical Properties: Atomic structure of substance, behavior in the presence of other chemicals.

Physical Change: a substance changes as it passes through the various phases but the chemical composition does not change.

• No new substance is produced.

• A change in size, shape, or phase without a change in composition. Its chemistry is unchanged.

• Little energy lost or gained

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Example: Breaking a chair.

Chemical Change: change in which a substance becomes another substance with different properties.

• Change in the composition of matter.

• A new chemical is formed with completely different properties.

• Cause the release of energy in the form of heat, light, or electricity. Example: Burning wood or paper.

Chemical changes

HCllll + CaCO3 ----> CaCllll2 + H2O + CO2 HCl + Zn ---> ZnCl2 + H2 + H2O

CuSo4 + Na2SiO3 ----> CuSiO3 + NaSO

Evidence of Chemical Change

1. Gas being released (bubbles, fizzing) 2. Color change 3. Heat released (exothermic reaction); temperature increases and container feels hot/warm or absorbed (endothermic reaction); temperature decreases and container feels cold 4. Light or other form of energy lost or gained 5. Solid or precipitate formed 6. Volume change

CHEMICAL BONDS

• There are three different types of bonds: Ionic Bonds; Covalent Bonds; Hydrogen Bonds

• Most atoms combine to complete an outer energy level of electrons. Generally, this number is eight electrons.

• Atoms may share, gain, or lose electrons in order to complete the outer energy level and to become more stable chemically (happy).

• When atoms combine chemically, a bond is formed that holds the atoms together. 1.Ionic Bonding: Ions are atoms that do not have the same number of protons as electrons. They lose or gain electrons.

• When they lose electrons they end up having more protons than electrons thus making the atom positive in charge.

• When they gain electrons they end up having more electrons than protons thus making them negative in charge. They are no longer electrically neutral.

Net charge = # of p - # of e- of an atom. Example: Mg + O 12p - 10e = 2p = 2+ e- 12p Mg =2+ O = 2- Electrostatic Force: Opposite charges attract and ions are held together by their opposite charges. This is an ionic bond. The stronger the charge, the stronger the bond.

12p

8p

9

+ 1+ 1-

+ 2+ 2-

2. Covalent Bonding: Most atoms do not lose or gain electrons. They do not transfer electrons. They share. + H + Cllll HCllll

When atoms share electron pairs to make a molecule, this is a covalent bond. • Atoms bond covalently, the resulting particle is called a molecule.

• A molecule is different from the particle formed by ionic bonding.

• The substance formed through ionic bond is an orderly arrangement of ions. 3. Hydrogen Bonds: Weak bonds that form between molecules of water, temporary polar bonds.

Polar

Hydrogen Bond

Hydrogen Bond

ENERGY OF CHEMICAL REACTIONS

• Energy is always involved in a chemical reaction. Sometimes energy is absorbed and sometimes released in the form of heat and/or light.

1. Endothermic Reaction: A chemical reaction in which energy is absorbed. Example: Decomposition of NaCl (salt). Fig.1. y Energy ..................................Heat absorbed... x

2. Exothermic Reaction: A chemical reaction in which energy is released.

Na

Cl

Mg

O

H

Cllll H

Cllll

H

O

H O

H

H

O

H

H

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Example: burning, combustion, formation of O2 with yeast and hydrogen peroxide. Fig. 2. y Energy

.............................................................. Heat released x

Catalyst A substance that speeds up a chemical reaction but does not take part in the reaction.

Activation Energy

The energy needed to climb to the top of the "energy hill."

Types of Chemical Bonds

Atoms form single bonds, and some can form double and/or triple bonds. 1) Single Chemical Bond -- made between two electrons (one pair). One electron from one atom and one electron from another atom. x Symbolized with 2) Double Chemical Bond -- made between four electrons (two pairs). Two electrons from one atom and two electrons from another atom. x Symbolized with x 3) Triple Chemical Bonds -- made between six electrons (three pairs). Three electrons from one atom and three electrons from another atom. x x Symbolized with x

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Chemical Equations

A chemical equation uses chemical symbols and formulas as a short way to describe a chemical reaction. It’s a way for chemists and scientists to be able to read and understand chemical reactions just like musicians can read and understand a piece of music written in music notes. There are four types of chemical reactions:

1. Synthesis Reaction Two or more simple substances combine to form a new, more complex substance. A + B ���� AB Example: 2H2 + O2 � 2H2O

2. Decomposition Reaction

A complex substance breaks down into two or more simpler substances. It is the reverse of a synthesis reaction. AB ���� A + B Example: 2H2O �2H2 + O2 3. Single-Replacement Reaction An uncombined element replaces an element that is part of a compound. A + BC����AC + B Example: 2Na + 2H2O � 2NaOH + H2 4. Double-Replacement Reaction Different atoms in two different compounds replace each other. In other words, two compounds react to form two new compounds by rearranging themselves (switching places). AB + CD ���� CB + AD Example: MgCO3 + 2HCllll � MgCllll2 +H2CO3

Magnesium carbonate + Hydrochloric acid � Magnesium chloride + Carbonic acid Carbonic acid decomposes to water and carbon dioxide: MgCO3 + 2HCllll � + H2O + CO2

BALANCING CHEMICAL EQUATIONS

Note: According to the Law of Conservation of Mass, the number, the type, and the mass of the atoms of the reactants is equal/same to the number, type, and mass of the products. Based on this law, we balance chemical equations by placing a coefficient (number) in front of the chemical formula (molecule). We never tamper with the subscripts. Example: H2 + O2 ------> H2O 2 2 2 1

The O is not balanced. To balance it, place a coefficient of 2 in front of the water molecule on the product side of the equation. H2 + O2 ------> 2H2O

2 2 4 2

The goal was to balance the O on both sides of the equation and that was accomplished but in the process of balancing the O, the H got unbalanced. The next step is to balance the H. Place a coefficient of 2 in front of the H2 molecule on the reactant side. 2H2 + O2 -----> 2H2O 4 2 4 2

**The equation is now balanced! The same number of atoms on both sides.

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Valences and Oxidation Number of Some Elements # Element Chemical

Symbol Physical

Properties Valence

Electrons # Electrons

Gained or Lost Oxidation

#

1 Aluminum Al Silvery metal 3 Lost 3 +3

2 Argon Ar Colorless gas 8 0 N/A

3 Beryllium Be Silvery metal 4 Lost 2 +2

4 Boron B Yellowish-brown crystal

5 Lost 3 +3

Bromine Br Liquid-evaporates rapidly to purple-

brown gas

1 Gained 1 -1

5 Calcium Ca Silvery metal 2 Lost 2 +2

6 Carbon C Black crystal 6 Lost or Gained 4

+4 or -4

7 Chlorine Cl Yellow-green gas 7 Gained 1 -1

8 Copper Cu Reddish metal 2 Lost 2 +2

9 Fluorine F Pale-yellow gas 7 Gained 1 -1

10 Helium He Colorless gas 2 0 N/A

11 Hydrogen H Colorless gas 1 Lost 1 +1

12 Iron Fe Grayish metal 2 Lost 2 +2

13 Lead Pb Bluish white metal 2 Lost 2 +2

14 Lithium Li Silvery metal 1 Lost 1 +1

15 Magnesium Mg Silvery metal 2 Lost 2 +2

16 Mercury Hg Silvery, white, metallic

2 Lost 2 +2

17 Neon Ne Colorless gas 8 0 N/A

18 Nitrogen N Colorless gas 5 Gained 3 -3

19 Oxygen O Colorless gas 6 Gained 2 -2

20 Phosphorus P Red or yellow crystal

5 Gained 3 -3

21 Potassium K Silvery white metal

1 Lost 1 +1

22 Silicon Si Silvery crystal 4 Lost or Gained 4

+4 or -4

23 Silver Ag Silver-metallic 1 Lost 1 +1

24 Sodium Na Silvery metal 1 Lost 1 +1

25 Sulfur S Yellow crystal 6 Gained 2 -2

26 Zinc Zn Bluish pale grey metallic

2 Lost 2 +2

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Valences and Oxidation Number of Some Radicals

# Name of

Radical Symbol Elements Present and # of

Atoms of Each Ratio

Of Elements

# Electrons Gained or Lost

Oxidation #

1 Nitrate NO3 Nitrogen: Oxygen 1:3 Gained 1 -1

2 Carbonate CO3 Carbon: Oxygen 1:3 Gained 2 -2

3 Hydroxyl OH Oxygen: Hydrogen 1:1 Gained 1 -1

4 Phosphate PO4 Phosphorus: Oxygen 1:4 Gained 3 -3

5 Bicarbonate HCO3 Hydrogen:Carbon:Oxygen

1:1:3 Gained 1 -1

6 Sulfate SO4 Sulfur:Oxygen 1:4 Gained 2 -2

7 Ammonium NH4 Nitrogen:Hydrogen 1:4 Lost 1 +1

CHEMICAL FORMULAS AND THEIR ABBREVIATIONS

# FORMULA NAME # FORMULA NAME

1 H

Hydrogen 22 NH4OH Ammonium Hydroxide

2 O

Oxygen 23 Ag Silver

3 C

Carbon 24 AgNO3 Silver Nitrate

4 CO2

Carbon Dioxide 25 Fe Iron

5 OH

Hydroxyl Radical 26 KBr Potassium Bromide

6 HCl

Hydrochloric Acid 27 S Sulfur

7 H2SO4

Sulfuric Acid 28 FeS Iron Sulfide

8 HNO3

Nitric Acid 29 Hg Mercury

9 Sn

Tin 30 HgO Mercuric Oxide

10 Cl

Chlorine 31 Na Sodium

11 Zn

Zinc 32 NaOH Sodium Hydroxide

12 Cu

Copper 33 Mg Magnesium

13 Al

Aluminum 34 I Iodine

14 SO4

Sulfate Radical 35 N Nitrogen

15 K

Potassium 36 P Phosphorus

16 Br Bromine 37 CaCl Calcium Chloride

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17 NO3

Nitrate Radical 38 NaCl Sodium Chloride

18 Ca

Calcium 39 PO4 Phosphate Radical

19 CO3

Carbonate Radical 40 ∆ Heat

20 CaCO3

Calcium Carbonate 41 ----> Yields (gives)

21 NH4

Ammonium Radical

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Points to Remember States or Phases of Matter • Solids – atoms vibrate slightly in position (in same place). The molecules of a solid can’t move very

much but they can vibrate. When a solid changes into a liquid, its molecules can move around and change positions.

• In solids, such as ice, the molecules are organized in crystal lattices. As it warms up, the molecules in the frost crystals move faster and break apart from each other.

• Crystal lattice; molecules in crystals are in an organized pattern forming a crystal lattice.

• Liquids – atoms have more space between them and move past one another. In liquids, such as water, the molecules are not organized. Instead, they float around.

• Gases – atoms (molecules) have a lot more space between them and move very fast and independently of one another.

• Plasma – the 4th state of matter, has no definite shape or volume and its particles are broken apart. Found in very high temperatures like the temperatures on stars (including the sun). On Earth, it is found naturally in lightning and fire. Man made, in fluorescent light.

• Boiling – from liquid to gas.

• Freezing – from liquid to solid.

• Melting – from solid to liquid.

• Condensing – from gas to liquid.

• Sublimation – from solid to gas (skipping the liquid phase).

• Refer to examples with jar for the movement of solid, liquid, and gas particles.

• Ice to water to steam = physical change (not chemical).

• Melting point; boiling point; freezing point can identify an unknown substance.

Atoms

• Protons (positive charge) and neutrons (no charge) are found in the nucleus of the atom and make up the mass of the atom.

• Electrons are orbiting around the nucleus and have a negative charge.

• An electron is very small compared to a proton and compared to the whole atom. • Four forces keep the atom and the subatomic particles together: electromagnetic force; strong

force; weak force; gravity (what is their role?)

• Evaporation is when a liquid changes to gas (this is a physical change, not chemical).

• Condensation is when a gas changes to liquid (this is a physical change). • Freezing (solidification) is when a liquid changes to solid (this is a physical change).

• Melting is when a solid changes to liquid (this is a physical change).

• Sublimation is when a solid changes directly to gas without turning into liquid (ex. Dry ice to gas C02.)

• When matter changes from one state to another, it is not a chemical change. It is a physical change.

• Baking a cake is like making NaCllll (salt). It is a chemical change.

• Burning something (wood) is an exothermic chemical reaction and the total weight of the smoke + the ashes is equal the weight of the wood before it burned.

• Compounds are formed when two or more different atoms are chemically bonded.

• Molecule is the smallest unit of a substance, which retains all the physical and chemical properties of that substance.

• Isotopes are atoms of the same element with the same number of protons but different number of neutrons (and thus, different atomic mass/weight). Example: 6p; 6n and 6p; 7n.

• Ions are atoms that have either lost or gained electrons and are positively or negatively charged.

• CH4 (Methane gas) released by cattle, increase.

• Oxygen atoms and Hydrogen atoms can combine in five different ways but only two of the following are compounds; water and hydrogen peroxide. Check definition of compound above. 1) Oxygen gas: O + O => O2 2) Hydrogen gas: H + H => H2 3) Water: H + H + O => H2O 4) Ozone: O + O + O => O3

5) Hydrogen Peroxide: H + H + O + O => H2O2

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• Chemical symbols have one letter; two letters; three letters. If one letter, it is capitalized; if two letters, the first is capital, the second is lower case; If three letters, the first is capital and the other two are lower case.

• Inert or Noble Gases are the elements in the last column (family/group #18) of the Periodic Table

• Inert or Noble Gases are called that because they do not react with other elements on the Periodic Table

• Groups or Families are the columns in the Periodic Table and the Elements found in the same family (column) have similar chemical properties and react the same.

• The law of conservation of mass or matter, states that the total mass of the reactants in a chemical reaction is equal to the total mass of the products. Example: If 3g of one reactant combine completely with 10g of a second reactant to form a product, the mass of the product formed by this chemical reaction will equal to 13g.

• The law of conservation of mass or matter, also states that the number of atoms of the reactants in a chemical reaction, is equal to the number of the atoms of the products.

• In other words, the number of atoms and the mass or weight of the substances in a chemical reaction, do not change.

• In a chemical equation the mass of the reactants is a controlled factor (because it does not change).

• Based on the law of conservation of mass we balance equations because the total number of atoms on the product side of the equation equals to the total number of atoms on the reactant side of the equation.

• In an endothermic reaction the container with the chemicals involved in the reaction will get cold (heat absorbed from the environment).

• In an exothermic reaction the container with the chemicals involved in the reaction will get hot or warm (heat liberated to the environment).

• Identify Metals, Nonmetals, and Noble or Inert gases on the Periodic Table

• Polymers are long chain molecules something like putting similarly sized blocks in a repeating pattern. • Salt crystals like the ones we examined in the lab are cube-shaped because the atoms in a sodium

chloride crystal are arranged in a pattern that makes a cube and they are made of ions. The atoms are arranged in repeating patterns and cannot change position.

• Chemical Change is when a new substance or material is formed is different chemical properties than before. Example: Hydrogen gas + Oxygen Gas = Water. Check your Chemistry Notes of Evidence of Chemical Change (color change or formation of gas for instance).

• Catalyst a substance that helps a chemical reaction take place but does not change itself.

• Ex. 2H202 + catalyst ---> 02 + 2H20 + catalyst • Chemical reactions usually release (exothermic reaction) or absorb energy (endothermic reaction)

in the form of heat. Organic Chemistry

• Living Organisms require a variety of molecules; some molecules contain carbon and some do not.

• The molecules that make up organisms and control the biochemical reactions that take place within them are usually large molecules, such as DNA, proteins, carbohydrates, and Lipids (fats & oils).

• Organisms also require simple substances, such as water and salt, to support their functioning. • Control in an experiment is the part of the experiment that does not change. Example: Two cups with

vinegar and you add baking soda to one cup. The control is the cup without the baking soda.

Acids and Bases • Acids and bases are tested with litmus paper.

On the pH scale acids are less than 7 and bases are above 7. A solution of pH 6.9999 and below is an acid. A solution of 7.1 to 14 is a base. Example: pH 3 is an acid. PH 9 is a base.

• pH close to 7 indicates that the acid or base is weak (ex. 6 & 5 = weak acid; 8 & 9 = to weak base). • pH close to the two ends of the scale indicates that the acid or base is strong (ex. 1 or 2 = strong acid;

13 or 14 = strong base).

• pH measures hydrogen ion concentration.

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ACTIVITIES 1. Research why plants and animals need simple molecules such as water. 2. How can you demonstrate that water is in fruits and vegetables?

3. How do you know that there is salt in your body.

Organic Chemistry Review

1. Living organisms contain many carbon-based molecules 2. The carbon atom is able to make many kinds of molecules in living organisms because of:

a) Its ability to form covalent bonds with itself as well as with many other elements. b) Its ability to form four single bonds. c) Its ability to form single, double, and triple bonds.

3. There are six elements all together including carbon that are found in large numbers in the molecules of living organisms (they are the main components of most living organisms): carbon; oxygen; hydrogen; nitrogen; phosphorus; sulfur (come over here now play soccer)

4. You can demonstrate the presence of carbon in an object by burning it. The black, charred remains are evidence of the presence of carbon.

5. Carbon combines with other elements to form the greatest variety of compounds in living things and can form many kinds of complex molecules.

6. Carbon molecules make the ring (the skeleton) of a glucose molecule. 7. Most of the molecules in all of the organisms are made of only a few elements (the six elements, see

#3 above). 8. Carbon combines with other elements to form the greatest variety of compounds in living things. 9. Protein molecules are the largest molecules known. 10. Fat in living things is made up of very large molecules. 11. Other large molecules are fats, carbohydrates, DNA/RNA. 12. pH measures the hydrogen ion concentration in a solution. 13. The metals are found on the left and center of the periodic table, the nonmetals are like a staircase

towards the right end of the periodic table, and Inert gases are the last column (right) of the periodic table.

14. Solids have definite shapes while liquids and gases do not because their atoms vibrate slightly in position when in the solid state.

15. The movement of molecules increases when a solid changes to a liquid. 16. The movement of molecules increases when a liquid changes to a gas. 17. The total number of grams of the reactants is equal to the total number of grams of the products in a

chemical reaction. 18. Molecules of living organisms contain at least one carbon atom.

19. A compound is two or more different elements chemically combined. 20. Fat is a substance found in living things and is made up of very large molecules.

21. Any two atoms of the same element have the same number of protons. 22. Carbon can form single, double, or triple bonds.

Astronomy Review

1. Asteroids are found between Mars and Jupiter. 2. Light from the Sun reflects off the moon and planets like Venus. 3. Temperature affects the color that stars omit. 4. During a full moon, one side of the Moon is dark because it is shaded from the direct light of the Sun.

5. One AU (astronomical unit) is determined by the distance between the sun and the Earth (150 million km, 1.5x108 km or 93 million miles). If you want to represent this in meters, it will be 1.5x1011 m. 6. The Sun is like the other stars in the Milky Way because they all revolve around a common center. 7. The Sun is located on the rim of the Milky Way galaxy. 8. The temperature of a star is determined by its color. Blue for hot, orange and red for cool. 9. The Sun is like other stars in the Milky Way because they all revolve around a common center.

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10. We use the AU to measure distances in our Solar System but the light year to measure distances beyond our solar system (greater distances), for example if we want to measure the width of the Milky Way or the distance between galaxies. 11. Stars form clusters within galaxies, and galaxies form clusters within the universe. 12. The mass of a body affects the gravitational force between bodies in our Solar System. The greater the mass, the greater the gravitational force. The greater the distance, the smaller the gravitational force. 13. If planets have a different pattern of movement through the sky than stars, to prove this, then you should draw the location of the planets you are testing in relation to nearby stars each night for a few months. 14.The Sun exerts the greatest gravitational pull on other objects in the Solar System. More than Jupiter, Earth, and the Moon. 15. Moonlight is created from the Sun. It is the reflection of the sunlight. Therefore, if you want to demonstrate this with models, you should shine a flashlight on a ball that represents the moon. 16. During a full moon, one side of the Moon is dark because the dark side of the Moon is shaded from the direct light of the Sun. 17. Earth and Mars are both composed mostly of rock. 18. Jupiter, Saturn, Uranus, and Neptune are considered the gas planets. 19. When you observe the planets in the sky at different times every night, you will find that they are located in different spots. 20.The stars in the Milky Way have different sizes and colors but the same shape (spherical). 21.To classify galaxies, we look at their shape. 22. Most stars are located in large clusters that are separated by great distances. 23. Venus does not have any moons. It is smaller that the Earth, its composition is mostly rock, and its temp. is 462oC. 24.The coolest (not much energy left) stars appear red and the hottest stars (new stars full of energy) appear blue. 25. If the Moon were not affected by gravity it would travel in a straight line away from Earth. 26. A moon orbits a planet. 27. A planet orbits the sun. 28. When forces applied to an object, if the forces are unbalanced (not equal) the object will move. If the forces are balanced (equal in all directions) the object will stay stationary (will not move). 29.The velocity of a moving object like a car is determined by its speed and direction. 30.To calculate speed, you should divide the distance by the time. 31. Independent variable in an experiment is the factor that changes the results of the experiment. 32. Learn the main characteristics of each planet. 33. The moon would travel in a straight line away from Earth if it was not affected by gravity. 34. A galaxy is a collection of many billions of stars. 35. Gravitational force is necessary for the creation of stars and galaxies. 36. Earth and Mars are both composed mostly of rock. 37. The core of a comet is mostly ice. 38. The gravitational force between bodies in our Solar System is affected by the masses of the bodies. The bigger the mass, the greater the gravitational force. 39. The four planets closest to the Sun are called the inner planets. The next group of four planets are considered outer planets. 40. The inner planets are small and rocky, and the outer planets are large and made mostly of gases. The gaseous planets have rings and longer years, while the rocky planets do not and have shorter years because they orbit the Sun in less time. 41. Between Mars and Jupiter is the asteroid belt. It is a region full of asteroids, which are like the rocky planets because they are made of chunks of rock and some ice and orbit the Sun.

Physics Review

1. Density = mass / volume. 2. The unit of density is grams over milliliters or cubic centimeters (g/ml or g/cm3). 3. Average speed = total distance divided by total time. 4. The direction and size of the buoyant force acting on a floating object in water is upward and equal to the weight of the water displaced by the object.