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8/2/2019 Science Exam Reviewer

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Properties of Matter

Chemical Properties

Reactivity- ability to readily interact chemically with other substances

- ex: rusting, giving off odors, changing color, new substance formed, formation of gas/fumes orprecipitate, absorption/release of heat

Flamability- ability to produce a flame

Physical Properties

Density- amount of matter in the volume of a substance- intensive property

Melting Point- the temp. at which a solid turns into a liquid- intensive property

Boiling Point- the temp. at which a liquid turns into a gas- intensive property

Thermal and Electrical Conductivity- metals with high conductivity are conductors, those with low conductivity are insulators

Malleability- the ability to be morphed without breaking/flattened into thins sheets

Ductility- the ability to be stretched into wires or threads- intensive property

Intensive Properties

- don’t depend on the size/amount of the substance

- Boiling Point, Melting Point, Density, Taste, Color, Luster, Ductility

Extensive Properties- depends on the size/amount of the substance

- Mass, volume, length

Separation Techniques

Physical manipulation

- manually separating/sorting- Ex: Separating iron nails and screws



Filtration- use of a filtering material that will let only same components through

Decantation- separating of the components that form distinct layers (immiscible)- Ex: Pouring one layer out of an oil+water mixture

Simple Distillation- components are separated due to the differences in their boiling points- let water evaporate then let it condense

Fractional Distillation- special process used for the preparation of fuel and other petroleum products

Evaporation- involves heating the mixture to separate the solid residue from the liquid- to get the solute from a solution

Use of Magnet

Paper Chromatography

Changes in Matter

Physical Change

- the molecules of the material undergoing physical change retain their identity. No new substance is

formed. The change is only in SIZE, SHAPE, or PHASE of the material

Chemical Change

- the molecules of the substance involved in a chemical reaction change their identity because a.) the

atoms that constitute the molecules may be rearranged, b.) atoms may be removed from the

molecule, or c.) atoms may be added to those in the molecule. Hence, a new substance or substances

are formed, but the atoms RETAIN their identity.

Atomic Models and Scientists

Democritus- came up with the word atom or “atomos”, which means indivisible in Greek - proposed that: Atoms can be in any shape

Atoms are infinite and constantly movingAtoms can combine with other atomsAtoms are indivisible



John Dalton

- first atomic theory:

1. Matter is composed of tiny indivisible particles called atoms.2. Atoms of a particular element are identical.

3. Atoms of different elements have different masses.4. Atoms of different elements can join to form compounds.

J.J Thompson

- discovered the electron- concluded that there must be particles within the atom even without confirmation of theirexistence

- proposed the plum pudding model> “atoms contain smaller sub-atomic particles” (Trivia: Quarks)

Ernest Rutherford

- discovered the nucleus> protons> called the area, nucleus

> the atom is mostly empty space> the nucleus may be tiny, but contains 99.99% of the atom’s mass

Niels Bohr

- came up with the planetary model of the atom> each electron in an atom has a fixed amount of energy> energy keeps an electron moving around the nucleus within a specific region

called energy levels



James Chadwick

- discovered the neutron> nucleus contains neutrons> neutrons have same mass as protons but neutrons have no electrical charge> electrons move constantly around the nucleus

Erwin SchrÖdinger

- came up with the quantum mechanical model of theatom/Electron Cloud model

Atomic Anatomy

- an atom has 3 basic particles: 1. Proton (nucleus), 2. Neutron (nucleus), and 3. Electron (outside thenucleus)

- atomic number = # of protons = * # of electrons (* if atom is neutral)

- most atoms are neutral (+ = -), but some atoms gain or lose an electron. When this happens, the atombecomes charged; ION

Ex: Fluorine atom + 1 electron F-Sodium atom – 1 electron Na +

- mass number = # of protons + # of neutrons

- # of neutrons = Mass number – Atomic number

Element Atomic # Mass # # of Protons # of Electrons # of Neutrons

Hydrogen 1 1 1 1 0

Carbon 6 12 6 6 6

Oxygen 8 16 8 8 8

Atomic Anatomy

- an atom has 3 basic particles: 1. Proton (nucleus), 2. Neutron (nucleus), and 3. Electron (outside thenucleus)

- atomic number = # of protons = * # of electrons (* if atom is neutral)



- most atoms are neutral (+ = -), but some atoms gain or lose an electron. When this happens, the atombecomes charged; ION

Ex: Fluorine atom + 1 electron F-Sodium atom – 1 electron Na +

- mass number = # of protons + # of neutrons

- # of neutrons = Mass number – Atomic number

Element Atomic # Mass # # of Protons # of Electrons # of Neutrons

Hydrogen 1 1 1 1 0

Carbon 6 12 6 6 6

Oxygen 8 16 8 8 8

* atomic number determines the type of element

Isotopes

- atoms of an element with different number of neutrons AND different masses

Ex: Hydrogen 1 (protium) – 1 proton, 0 neutronsHydrogen 2 (deuterium) – 1 proton, 1 neutronHydrogen 3 (tritium) – 1 proton, 2 neutrons

* neutron = 1.009 amu electron = 0.0005 proton = 1.007 amu

- unstable atoms/isotopes are radioactive: their nuclei decay (nuclear decay)

- uses of Isotopes: Bone scans, Medicine (Chromium, Iodine, etc.)

Ions

* cations – positive ions (protons > electrons)anions – negative ions (protons < electrons)

* only electrons can transfer from one atom to another. Ionic compounds are formed by cations andanions.

Ex: O-2

x = number of protons, x + 2 = number of electrons

- when an atom loses or gains an electron, it becomes charged; IONS

Atomic Mass

[ (% abundance of isotope) (mass of isotope) + (% abundance of isotope)

(mass of isotope) + …]



Ex: Chlorine. Give the abundance of Chlorine’s Isotopes.

Given: Cl 35 – 34.969 amu, Cl 37 – 36.966 amu, Atomic Mass = 35.453 amu

35.453 = [ (x) (34.969) + (1-x) (36.966) ]

35.453 = 34.969x + 36.966 – 36.966x36.966 – 35.453 = 36.966x – 34.969x

1.513 = 1.997x

X = 1.513 / 1.997X = 0.7576364

* Sig. Figs!X = 75.76%, 1-X = 24.24%

Cl35

‘s abundance is 75.76% while Cl

37

‘s abundance is 24.24%.

Laws of Motion

Force

- push or pull exerted on an object- can move objects- can stop the motion of an object- can change the direction of motion- can change the shape or form of an object- Sl Unit Newton (N)

Some terms Sir mentioned:- elastic limit- yield strength- normal force (cancels out the gravitational force)

* an object will not change its motion by itself, an external force is required to cause this change. Unlessit is in motion with constant velocity

Aristotle

- scientist from Ancient Greece- believed that, except for heavenly bodies, “the natural state of things was a state of rest, a force was

required to keep objects in motion.”

Galileo Galilei

- scientist from Italy- inferred that, “an object in motion would tend to keep on moving if there was no retarding force

acting on it.”



- gave the term “Inertia” to this tendency of an object to keep moving- was able to see what would happen in the absence of friction

Isaac Newton

- picked up where Galileo left of - formulated 3 Laws of Motion: Inertia, Acceleration, and Action-Reaction

Newton’s 1st

Law of Motion: Law of Inertia

- refinement of Galileo’s ideas - “An object at rest tends to remain at rest. If in motion, it will tend to move at constant speed in a

straight line unless it is acted upon by an unbalanced external force.”

* an object’s mass is a measure of its Inertia

- ↑m = ↑Inertia, ↓m = ↓Inertia - hefting – shaking two objects to see which is heavier

*Inertia is the property of an object to resist changes in its state of motion or rest

* ∑ Net Force = 0

if at rest, V=0

if in motion, at constant velocity

Newton’s 2nd

Law of Motion: Law of Acceleration

- “An object’s acceleration is directly proportional to the Net Force acting on it and is inversely

proportional to the object’s mass. The object always accelerates in the direction of the Net Force.”

* F = ma

F – Net Force in N, m – Mass in kg, a – Acceleration in m/s2

- ↑F = ↑A, ↓F = ↓A, ↑M = ↓A, ↓M = ↑A

Newton’s 3rd

Law of Motion: Law of Interaction/Action-Reaction

- “For every action, there is an equal and opposite reaction.”

- forces in Nature always come in pairs- action-reaction forces act on different objects

Force

- Can make objects move, speed up, slow down, or simply change its direction

- A push or a pull



Objects that are not in motion doesn’t necessarily mean they are not acted upon by forces. For

stationary objects, the forces are balanced, so there is no motion.

Contact Forces- Exerted between objects that are in close contact.

Examples: Friction, Force that makes huge ships float, Force that enables airplanes to fly

Noncontact Forces- Exerted between objects that aren’t even touching

Examples: Gravity, Magnetism, Strong Force, Weak Force

The Fundamental Forces

Gravitational Force- Formulated by Isaac Newton

- Affects anything that has mass

- An attraction, or pull between objects

- The strength of the force depends on the masses of the objects and their separation

- Always attractive

Dependence on Mass

- One’s weight is just our planet’s gravitational force on that him

- If one’s mass changes, his weight changes as well

- Any attraction (gravitational) between you is negligible. If one gets close enough to a really large

mass (like a planet), you will get stuck to it

Dependence on Distance

- The closer two objects are, the greater the gravitational force is. But as the separation

decreases, the gravitational force quickly decreases

- There are billions of objects in our universe that are more massive than our own planet, but due

to their immense distance, the force they exert on us is negligible

Electromagnetic Force

- Electric and magnetic forces are very closely related and are unified into one force, the

electromagnetic force

- For charged objects, the rule is that like charges (both positive ot both negative) repel, and

unlike changes (positive and negative) attract

- This force can be more than a billion times stronger than gravity. It is dependent on the amount

of charge possessed by objects. It also shows a dependence on distance. But unlike gravity, this

force can be either repulsive or attractive

Examples: Plastic comb attracting your hair, Electrons revolving around the nucleus

We never touch anything. We merely experience electromagnetic forces of repulsion

Weak Force- Not the weakest of the four fundamental forces. It’s actually stronger than gravity.

- Only active at distances less than 10 -18

- Exerted between a class of particles called leptons and hadrons



- An electron is an example of a lepton, and the proton and neutron are examples of hadrons

- Tends to cause nuclei and elementary particles to break up or became unstable; beta decay

Strong Force- Strongest of all fundamental forces

- Only effective at very short distances (10-25)

-

At great distances, this force is negligible- Without this force, the protons would quickly fly apart and the atom would disintegrate

It takes a tremendous force to overcome the strong force. But if it is overcomes, it results in the

splitting of nuclei to form lighter nuclei. This process, known as nuclear fission, releases

tremendous amounts of energy. This is what causes the immense power of the atomic bomb.

Living Things

Levels of Organization

1. Atoms

Smallest part of matter2. Molecules

2 or more bonded atoms

Form compounds3. Macromolecule

Very large moleculesProteins, fats, carbohydrates, DNA, nucleic acids4. Organelles

Tiny organsMade of macromolecules5. Cell

Made up of organellesBasic unit of structure & function6. Tissue

The same kind of cell working together7. Organs

Tissues that work together

8. Systems (Organ Systems)Organs that work together9. Organism

Entire living thingsUsually made of systemsMay be a single cell10. Population

Same types of organisms living together

11. Community

Several populations living together

Population interact12. EcosystemBiotic (living) community plus the abiotic(nonliving) features13. BiomeSimilar ecosystems on earth together14. BiosphereWhole living layer around the globe

Includes abiotic features



7 Characteristics of Living Things

1. Made of Cells * unicellular-- living things with only one cell. Examples: Amoeba, Bacteria, etc.multicellular-- living things with many cells. Examples: Hydrilla plant, Elodea plant

2. Need Food as Energy Source

- all organisms acquire energy and use energy* autotrophs (use sun's energy)heterotrophs (take energy from other living things, like food)

* helps produce ATP (immediate source of energy for performing activities)

3. Grow and Develop

- occurs through cell division and cell enlargement- some organisms grow, while some go through a cycle of change (like mosquitoes and butterflies)

4. Respond to Stimuli

- vital to any organism- helps: escape predators, find food, move to light, survival

Stimulus- anything that incites living things to action- more observable in animals than plants- Ex: Touching a hot metal lid makes us pull our hand away.- kinds of stimuli: Phototropism (light), Geotropism (gravity), Hydrotropism (water), Thigmotropism(touch)

5. Reproduce* organisms produce offspring like themselves- asexual reproduction (binary fission), or sexual reproduction

6. Perpetuate their kind through the Genetic Material* living things have the capability to maintain the identity of their kind through a chemical compoundknown as DNA- closest that living things can get to 'immortality'

7. Evolution

- one characteristic that distinguishes living things from nonliving things

- undergo genetic changes through time

Cells

- basic unit of structure of living things

- unit of function

- generally microscopic

- all actions we do are combined responses of millions of cells



2 Kinds of Cells: 1 Animal Cell and 2 Plant Cell

3 main parts of the cell:

Cell Membrane

- controls what goes in and out of the cell

- like the shell of an egg

Cytoplasm

- gel-like materials where all organelles are suspended in

- like the egg whites

Nucleus

- controls all the activities of the cell

- like the egg yolk

Other Organelles:

- Mitochondrion (produces energy; POWERHOUSE)- Ribosomes (produces proteins)

- Endoplasmic Reticulum (enables movement from one part of the cell to another; TRAMSPORT

SYSTEM) * Rough ER contains Ribosomes

- Golgi Bodies (stores and packages chemicals; FINAL PRODUCT)

- Lysosomes (breaks down worn out cell parts; removes wastes)

- Vacuoles (stores food, water, and other materials; RAW MATERIALS)

- Nucleolus (synthesizes proteins that are stored as RNA)

- Nucleoplasm (contains fibers made up of DNA)

Organelles in Animal Cells that aren't found in Plant Cells

1 Lysosomes (breaks down worn out cell parts; removes wastes. Usually not evident in Plant

cells)

Organelles in Plant Cells that aren't found in Animal Cells

1 Cell Wall (for support and protection)

2 Chloroplasts (stores sun light for photosynthesis)

3 Large Vacuole (stores the food, water, and etc. Some Animal cells contain small contractile

vacuoles)

Plant cells contain plastids (Chloroplasts, Chromoplasts)

Prokaryotic Cells and Eukaryotic CellsProkaryotes Eukaryotes



- Don’t have a membrane-bound nucleus - Have a membrane-bound nucleus/welldefined nuclei

- Unicellular - Unicellular OR multicellular

Examples: Bacteria, etc. Examples: Animal cells, Plant cells, etc.

Cell Theory; Prokaryotes and Eukaryotes

Characteristics Prokaryotes Eukaryotes

Nuclear

Membrane

Absent Present

DNA Single loop Multiple loopsarranged intochromosomes

Cell Membrane Present Present

Cell Wall Present Present only inplant cells

Ribosomes Present Present

Chlorophyll When present, itis not containedin chloroplast

When present(inplant cells), it iscontained inplant cells

Mitochondria,

Endoplasmic

Reticulum, Golgi

bodies, vacuoles

Absent Present

Cell Theory1. All organisms are composed of

cells.

2.

All basic chemical andphysiological functions are

carried out in the cell.

3. All cells are produced by the

division of preexisting cells.

Generalizations about Cells1. Cells are ALIVE

They take in energy and building

materials so that they canreproduce and repair themselves.2. The characteristic needs of an

organism are the characteristic

needs of its cells.

1590Hans andZachariasJanssen

producedfirst

1665Robert Hooke was thefirst to call spaces in cork“cells”.

1680’s Anton vanLeeuwenhoek

observed living

things throughsimple

1838MatthiasSchleidendiscovered that

plants are madeup of cells.

1839Theodor Schwanndiscovered that animals

are made up of cells.

1855Rudolph Virchowstated that livingcells come from

other living cells.



SOURCE: GOOGLE IMAGES, SIR FABELLO’S HANDOUTS

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