Transcript Chapter 2 Notes PowerPoint

Chemistry
Diamond
Water
Sugar
Diamond (carbon) = C
 Water = H2O
 Sugar = C6H12O6
The combination of carbon and water
contains the same elements as sugar.
. Elements: can’t be broken into simpler
substances (atoms.)

Sugar + water…would you drink this?
 Ash + water…would you drink this?
 Why? They contain the same elements
don’t they? Why don’t you get sugar when
you mix water with the coal?

The elements (carbon in coal; hydrogen
and oxygen in water) only combine as
sugar when chemical bonds form
 Sugar cannot be easily separated into its
components.

So…Can you break gold down
into a simpler substance???

NO…because it is an element!

Atoms are the basic building blocks of all
matter.
The structure of an atom
The center of an atom is called the nucleus
 All nuclei contain positively charged particles
called protons (p+).
 Most contain particles that have no charge,
called neutrons (n0).
Example: Carbon has 6 protons so its
atomic number is 6

The space surrounding the nucleus contains
extremely small, negatively charged particles
called electrons (e-)
 This region of space
is an electron cloud.
Because opposites
attract, the electrons are held in
the electron cloud by
the + nucleus.
Nucleus

Electron
energy
levels

Atoms contain equal
numbers of electrons
and protons;
therefore, they have
no net charge.
Particle
Location
Charge
Symbol
Electron
Surrounding
nucleus
-
e-
Neutron
Nuclei
None
no
Proton
Nuclei
+
p+
Compounds and Bonding
• A compound is a substance that is composed
of atoms of two or more different elements that
are chemically combined.
• Table salt (NaCl)
is a compound
composed of the
elements sodium
and chlorine.
How covalent bonds form
• A covalent bond
holds the two
hydrogen atoms
together.
• A molecule is a
group of atoms
held together by
covalent bonds.
It has no overall
charge.
Water
molecule
st
1
2 electrons in the
electron
shell
8 electrons in the 2nd electron
shell
18 electrons in the 3rd electron
shell
•Not notes! Just cool
•This is an actual
picture (the 1st
EVER) of a
molecule. This is a
picture of the
smallest thing ever
taken!
Pentacene is a polycyclic aromatic hydrocarbon consisting
of five linearly-fused benzene rings. Used in dyes and
solar cells.
How ionic bonds form
• An atom (or group of atoms) that gains or
loses electrons has an electrical charge and is
called an ion. An ion is a charged particle
made of atoms.
• The attractive force between two ions of
opposite charge is known as an ionic bond.
Writing chemical equations
• In a chemical
reaction, substances
that undergo
chemical reactions,
are called reactants.
• Substances formed
by chemical reactions,
are called products.
•CO2 + H2O-----yields----H2CO3 (carbonic acid) is
a sample chemical reaction in living things
•Reactants are on the left side of the equation,
while products are on the right side
Writing chemical equations
• A molecule of table sugar can be represented
by the formula:
C12H22O11.
•Atoms are neither created nor destroyed in
chemical reactions. They are simply rearranged.
•A mixture is a combination of substances in
which the individual components retain their
own properties.
Ex:
sand + sugar
• Neither component of the mixture changes.
Heterogeneous Mixtures
 A mixture that is NOT mixed
evenly throughout & each
component keeps its own
properties.
•Rocks
•Salad
•Chicken Noodle
•Soup
Mixtures and Solutions
• A solution is a mixture in which one or more
substances (solutes) are distributed evenly in
another substance (solvent).
•Ex. Sugar + Water +
Kool Aid
•Can’t separate
Phases of Matter
Solid
 Matter with definite shape & volume.
 Tightly packed particles that mainly
vibrate.
Liquid
• Matter with a definite
volume but no definite
shape.
• Particles flow freely
from one place to
another.
Gas
Matter that doesn’t
have definite volume
or shape.
 Particles move at
high speeds in all
directions

Heating Curve of Water
•100oC
•solid
•liquid
•gas
•0oC
•-20oC
•Time (Increasing)
•Heat Energy (Increasing)
Plasma
• State of electrically
charged free moving
particles.
Physical Changes
 The
form or appearance of matter
changes, but not its composition.
 Dissolving
 Changing
State/Phase
 Absorption
 Cutting/Tearing/Smashing
Chemical Changes
 Changing
from one substance into a new
substance.
 Color
change
 Forming a gas or solid
 Producing light
 Odors
 Giving off heat
 Absorbing heat
The Periodic Table

Classification of the Elements
Metals
 Most
of the elements are solid metals.
 Metals are usually shiny, malleable,
good conductors of heat & electricity
and ductile.

Metalloids
 Elements
that have some
characteristics of both metals &
nonmetals.
- Examples: Boron, Silicon, Antimony,
& Arsenic
Nonmetals
 Most
•Liquid O2
•Sulfur
nonmetals
are gases.
 Solid nonmetals
are brittle, poor
conductors, & not
easily shaped.
 97% of your body
is made of
nonmetals
Elements
Atomic Number
Shows the number of protons in the nucleus.
 Every atom of that element has only that
number of protons.

Mass Number



Number of protons plus neutrons.
Isotopes: Atoms of the same element with
different numbers of neutrons.
Examples: Hydrogen-1, Hydrogen-2, Hydrogen-3
Carbon-12, Carbon-14
 Used
to treat cancer & radioactive dating
Atomic Mass
The weighted average of the isotopes
of an element.
 Measured in mass units (u)

•Atomic Number
•47
•Ag
•Silver
•107.868
•Atomic Mass
•Chemical
•Symbol
The Periodic Table
* Arranged according to atomic number
and similar properties.
Periods
A row (horizontal) of elements.
 The properties gradually change
predictably across the period.

Groups/Families

Usually the vertical columns of
elements that have similar physical &
chemical properties.
3
4
Li
Be
11
12
Na
Mg
19
20
K
Ca
37
38
Rb
Sr
55
56
Cs
Ba
87
88
Fr Ra
Alkali Metals
Most reactive of the elements.
 Not naturally found by itself.
 Has a single electron in its outermost shell.
 Column #1

Alkaline Earth Metals
Commonly used in fireworks for the colors.
 Has 2 electrons in the outermost shell.
 Column #2

Transition Elements
• Wide variety of metals such
as coin & structural metals.
• Middle of the periodic table.
• Examples: Gold, Silver,
Mercury, Lead, & Copper
9
F
17
Cl
Halogens

35
Br

53
I
85

At
117

Bond with Alkali Metals
to form salts.
Have 7 electrons in
outermost shell.
Steal electrons from
other atoms.
Column #17
2
Noble Gases
He

10

Ne

18
Ar
36
Kr
54
Xe
86
Rn
118


Only naturally stable elements.
Have a full outermost shell of electrons (8)
Found in small amounts in the atmosphere.
Heated to produce colorful light.
Column #18
Carbon Compounds
 Foundation
for life
 Carbohydrates, Lipids/Fats, Proteins, &
Amino Acids.
 Hydrocarbons - long chains of Hydrogen
& Carbon atoms :Alcohols & Fuels
Law of Conservation of Mass
 The
mass of the reactants will equal the mass
of the products.
Energy in Reactions
1. Endothermic – reaction where energy
is absorbed.
2H2O + energy
2H2 + O2
2. Exothermic – reaction where energy is
released.
C6H12O6 + O2
H2O + CO2 + energy
Rates of Reaction (things that affect
the rate)
1. Temperature
2. Surface Area
3. Pressure
4. Catalyst – a substance that speeds up
a chemical reaction. (Enzymes)
Water
• Water resists changes in temperature.
• Water is one of the few substances that
expands when it freezes.
• Ice is less dense than liquid water so it
floats as it forms in a body of water.
Adhesion and Cohesion

Water is attracted to other water. This is
called cohesion.
water on a
penny!

Water can also be attracted to other
materials. This is called adhesion.
Caused by adhesion
the water runs along
the glass and does
not fall straight.
Fin