Transcript Introduction to Chemistry

Introduction to Chemistry
Chapter 2
Section 2.1
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:
mass
_______________ which is a
measure of the amount of material in
a substance, and
volume
_______________ which is the
amount of space an object
occupies.
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.
To date, there are 118 elements.
Not all are naturally occuring.
Elements are given symbols that
contain one, two, or three letters .
If the symbol has just one letter, it
is capitalized. For example: C
If the symbol has two letters, only
the first is capitalized, the second
is written in lower case.
For example: He
Take a Moment or Two:
• List everything you know about atoms,
elements, compounds, and mixtures.
– You may want to use a chart to keep yourself
organized. 
• Give three or four examples of each.
atom
An __________________
is the
smallest part of an element that
has all the properties of that
element.
Atoms are composed of three types
of particles:
Particle
Location
Charge Mass
Proton
Nucleus
+
1.67 x 10-24g
1amu
Neutron
Nucleus
0
1.67 x 10-24g
1amu
Electron
Outside
Nucleus
-
9.11 x 10-28 g
amu = atomic mass unit
Relative
Mass
0 amu
Electrons can be found at any
location away from the nucleus, but
they are more likely to be in certain
regions than in others. The regions
in space in which it is likely to find
electrons are known as
energy levels or orbitals.
Atoms tend to be most stable
when their outer energy level
contains eight electrons.
gain, lose or share
Atoms _______________
electrons in an attempt to obtain
eight outer (or valence) electrons.
Elements may combine
chemically to form ___________.
compounds
molecule is the smallest
A ___________
part of a compound that has all
the properties of that
compound.
mixture
A ___________
is a physical
combination of two or more
substances, each of which
retains its individual properties.
Compounds differ from mixtures in
the following ways:
Compounds
Mixtures
New Properties
Substances Keep
Original Properties
Separated Chemically
Separated Physically
Proportions Fixed
Proportions Vary
Examples????
The number of protons in an element
is indicated by the ______________,
atomic number
which is given the symbol Z.
Z
In neutral atoms, the number of
electrons is equal to the number of
protons.
Atomic mass
________________,
which is given the
symbol A, is equal to the number of
protons plus the number of neutrons.
A
The number of neutrons is thus the
atomic mass minus the atomic
number. Atomic Mass 58.933 = 59
Atomic Mass
rounded to whole #
59
Atomic Number
- 27
# of Neutrons
32
Atomic Mass Rounded Off
Example: Lithium
3
Atomic number
Atomic mass
7 amu
Number of protons
3
Number of electrons
3
Number of neutrons
4
Complete Symbol:
7
atomic number 3
atomic mass
Li
Remember! Atomic mass – Atomic number = # Neutrons
Isotopes
Forms of an element that have the same
number of protons, and electrons, but
different numbers of neutrons and different
masses are called ____________
isotopes .
For example: Hydrogen has three common
isotopes
1
1
3
1
2
1
H
Protium
H
Tritium - Which is Radioactive!
H
Deuterium
Your Turn. Complete the Chart
Isotope
Symbol
55
25
Atomic
Number
Atomic
Mass
Mass
Number
Protons
Neutrons Electrons
Mn
12
13
31
14
6
15
35
45
40
51
C
92
238.029
Ions
A charged particle is called a(n)
_______
.
ion
Ions are formed by the gain or the
loss of __________
electrons .
Positive Ions
If an atom loses electrons, it has
fewer negative charges than it has
positive charges, and thus becomes a
positively
___________
charged particle, known
cation . Metals, found on the
as a _______
_____
left side of the periodic table, tend
to form positive ions.
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
negatively charged particle, known
___________
as a _______
anions . Nonmetals, found on
right side of the periodic table,
the _____
tend to form negative ions.
Negative Ions
Right Side of Table
Example:
Sodium (Na) Ion – Loses one electron
Sodium Atom
Sodium Ion
# of Protons
11
11
# of electrons
11
10
symbol
+
Na
Na0 or Na Na+1 or 1+
Na
Example:
Sulfur (S) Ion – Gains two electron
Sulfur Atom
Sulfur Ion
# of Protons
16
16
# of electrons
16
18
symbol
S0
S-2
or
S2-
Your Turn….
Isotope
Symbol
35
17
Atomic
Number
Atomic
Mass
Mass
Number
Protons
Neutrons Electrons
Cl-1
13
14
55.847
26
53
8
16
12
23
74
54
8
Chemical Bonding
bond is a force that
A chemical _______
holds atoms together in compounds.
There are two major types of chemical
bonds:
Chemical Bonding
ionic bonds, electrons are
In _______
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.
Example of Ionic Bonding
F
Li
LiF
Example of Ionic Bonding
gained 1 electron
lost 1 electron
now 10 electrons
now 2 electrons
Li +1
F-1
LiF
A Demo and A Movie
• The demo—
NaHCO3 + HC2H3O2
• One I’m not allowed to do in school…
Sodium and Water
• One from history
http://www.youtube.com/watch?v=Hs22jH
61b3E
Chemical Bonding
covalent bonds, two nonmetals
In _________
share electrons.
Non-Metals
Examples of Covalent Bonding
H
H
HF
F
They aren’t usually very
exciting…
Ionic and Covalent Bond Movie