introduction to chemistry chapter 5 section 5.1 courtesy of mrs. wyckoff click here to play the...
DESCRIPTION
All matter has two properties: _______________ which is a measure of the amount of material in a substance, and _______________ which is the amount of space an object occupies. mass volumeTRANSCRIPT
Introduction to Chemistry
Chapter 5Section 5.1
Courtesy of Mrs. Wyckoff
Click Here to Play the Element Song!
Chemistry is the Study of
Matter
Matter is a substance: that has mass and occupies space!
All matter has two properties:
_______________ which is a measure of the amount of material in a substance, and
_______________ which is the amount of space an object occupies.
mass
volume
Weight is a measure of the force of gravity.
All matter is composed of simple substances that cannot be broken down by ordinary chemical means called elements.
Elements are given symbols that contain one or two letters. If the symbol has just one letter, it is capitalized. For example:
If the symbol has two letters, only the first is capitalized, the second is written in lower case.
C
He
An __________________ is the smallest part of an element that has all the properties of that element.
atom
Elements may combine chemically to form _____________.compounds
A ___________ is the smallest part of a compound that has all
the properties of thatcompound.
molecule
A ___________ is a physical combination of two or more substances, each of which
retains its individual properties.
mixture
Compounds differ from mixtures in the following ways:
Compounds Mixtures
New Properties Substances Keep Original Properties
Separated Chemically Separated Physically
Proportions Fixed Proportions Vary
Atoms are composed of three types of particles:
Particle Location Charge Mass Relative Mass
Proton Nucleus + 1.67X10-24g 1 amu
Neutron Nucleus 0 1.67X10-24g 1 amu
Electron OutsideNucleus
- 9.11X10-28g 0 amu
amu = atomic mass unit
Electrons can be found at any location away from the nucleus, but they are more likely to be in certainregions than in others. The regions in space in which it is likely to find electrons are known as energy levels or orbitals.
Each energy level is able to contain only a certain number of electrons. Electrons fill the energy levelsclosest to the nucleus first. When one energy level is filled, electrons must move to another energy levelfurther away from the nucleus.
1s2 2s2
Nucleus
2p6
When one energy level is filled, electrons must move to another energy level further away from the nucleus.
Secondshell
Helium2He
Firstshell
Thirdshell
Hydrogen1H
2He
4.00
Atomic Mass
(#p+ #n)
Atomic number(#p)
Element symbol
Electron-shelldiagram
Lithium3Li
Beryllium4Be
Boron3B
Carbon6C
Nitrogen7N
Oxygen8O
Fluorine9F
Neon10Ne
Sodium11Na
Magnesium12Mg
Aluminum13Al
Silicon14Si
Phosphorus15P
Sulfur16S
Chlorine17Cl
Argon18Ar
Electrons determine the chemical reactivity of an atom: Electron-shell diagrams of the first 18
elementsChemical reactivity depends mostly
on the number of valence electrons (in outermost shell).
Atoms are most stable when their outermost electron shell is filled with
8 electrons (or 2 for H and H).
Atoms tend to be most stable when their outer energy level contains eight electrons. Atoms gain, lose or share electrons in an attempt to obtain eight outer, or valence, electrons.
Nucleus
1s11s2
HydrogenHelium
Atoms tend to be most stable when their outer energy level contains eight electrons. Atoms gain, lose or share electrons in an attempt to obtain eight outer, or valence, electrons.
Nucleus
2s1
LithiumBeryllium1s2 2s2
Atoms tend to be most stable when their outer energy level contains eight electrons. Atoms gain, lose or share electrons in an attempt to obtain eight outer, or valence, electrons.
Nucleus
1s2 2s2 2p1
BoronCarbon2p2
Atoms tend to be most stable when their outer energy level contains eight electrons. Atoms gain, lose or share electrons in an attempt to obtain eight outer, or valence, electrons.
Nucleus
1s2 2s2 2p3
BoronNitrogen2p4
Oxygen
Atoms tend to be most stable when their outer energy level contains eight electrons. Atoms gain, lose or share electrons in an attempt to obtain eight outer, or valence, electrons.
Nucleus
1s2 2s2 2p5
BoronFluorine2p6
Neon
Click Here for animation of electron shell filling!
The number of protons in an element is indicated by the ______________,
which is given the symbol Z.
Z
atomic number
In neutral atoms, the number of electrons is equal to the number of protons.
________________, which is given the symbol A, is equal to the number of protons plus the number of neutrons.
Atomic mass
A
The number of neutrons is thus the atomic mass minus the atomic number.
Atomic Mass rounded to whole #
Atomic Number - 27
# of Neutrons
Atomic Mass 58.933 = 59
59
32
Atomic Mass Rounded Off
Example: Lithium
Atomic mass
Number of protons
Number of electrons
Number of neutrons
Complete Symbol:3Atomic number
7 amu
3
3
4
Li73
atomic mass
atomic number
Remember! Atomic mass – Atomic number = # Neutrons
IsotopesForms of an element that have the same number of protons, and electrons, but different numbers of neutrons and different masses are called ____________ .isotopesFor example: Hydrogen has three common isotopes
H11 Protium H2
1 Deuterium
H31 Tritium - Which is Radioactive!
Three Isotopes of Hydrogen
Characteristic H H H
Atomic # 1 1 1
Atomic Mass 1 2 3
# protons 1 1 1
# electrons 1 1 1
# neutrons 0 1 2
1
121 1
3
Ions
A charged particle is called a(n) _______ .
Ions are formed by the gain or the loss of __________ .
ion
electrons
Positive IonsIf an atom loses electrons, it has fewer negative charges than it has positive charges, and thus becomes a ___________ charged particle, known as a _______ . Metals, found on the _____ side of the periodic table, tend to form positive ions.
positivelycation
left
Positive Ions
Left Side of Table
Negative Ions
If an atom gains electrons, it has more negative charges than it has positive charges, and thus becomes a ___________ charged particle, known as a _______ . Nonmetals, found on the _____ side of the periodic table, tend to form negative ions.
negativelyanions
right
Negative Ions
Right Side of Table
Example: Sodium (Na) Ion – Loses one electron
Sodium Atom Sodium Ion
# of Protons
# of electrons
symbol
11 11
11 10
Na0 Na+1 Na+or
Na1+or Na
Example: Sulfur (S) Ion – Gains two electron
Sulfur Atom Sulfur Ion
# of Protons
# of electrons
symbol
16 16
16 18
S0 S-2 S--or
S2-
Chemical Bonding
A chemical _______ is a force that holds atoms together in compounds. There are two major types of chemical bonds:
bond
Chemical Bonding
In _______ bonds, electrons are transferred from a metal, which loses electrons, to a nonmetal, which gains electrons. The resulting ions have opposite electrical charges, and are strongly attracted to one another.
ionic
Example of Ionic Bonding
F Li
LiF
Example of Ionic Bonding
F-1 Li +1
lost 1 electrongained 1 electronnow 10 electrons now 2 electrons
LiF
Chemical BondingIn _________ bonds, two nonmetals share electrons.
covalent
Non-Metals
Examples of Covalent Bonding
H
FH
HF
Ionic and Covalent Bond Movie