Complete Test Preparation For GED Test

Physical science
Chemistry
May Oo Khaing
B.Sc(Hons: Physics)
M.Sc ( Physics)
Ph.D ( Nuclear Technology)
Matter
 What is Matter?
Matter describes everything that exists.
Matter has mass and takes up space. It can
interact with other matter and with energy,
and these interactions form the basis of
physical and chemical reactions. But what
actually is matter?
 Matters are composed of Atoms

✓ Matter is composed of atoms.

✓ All atoms of a given element are
identical.
✓ Atoms of different elements are
different and have different properties.
✓ Atoms are neither created nor
destroyed in a chemical reaction.
✓ Compounds are formed when atoms of
more than one element combine.
✓ A given compound always has the
same relative number and kinds of
atoms.
 Let’s look at the history of the atom…
✓ Atoms
You and everything around you are composed of tiny particles called atoms.

✓ Every solid, liquid, gas, and plasma is composed of neutral or ionized atoms.

• The term atom, which means indivisible,

was coined by Greek philosopher
Democritus (460–370 B.C.)
• Plato and Aristotle—who believed that
matter could be infinitely divided into
smaller and smaller pieces
• John Dalton formulated a meaningful
atomic theory.
 Structure of the Atom

✓ Protons, Neutrons, and Electrons

• An atom is composed of a nucleus
surrounded by electrons.
• The nucleus contains positively
charged particles called protons and
uncharged (neutral) particles called
neutrons.
• Electrons are the negatively charged
particles orbiting the nucleus.
Structure and Properties of Matter, including Atoms
✓ atoms are electrically neutral.( number of
protons =number of electrons)
Element
Molecule ✓ Number of protons = atomic number
✓ Mass number = no's of protons + no's
Compound neutrons
Molecule
✓ Mass of proton = 1 amu (atomic mass
unit)
✓ Mass of neutron = 1 amu ( atomic mass
unit)
1
✓ Mass of electron = amu ( atomic
1836
mass unit)
✓ the outermost electron shell (the orbit of
the electrons) are called valence
electrons.
( Charge of the nucleus= ?)
 Isotopes and Ions
Isotopes Ions
Isotopes are two or more types of atoms that An atom can lose or gain electrons and
have the same atomic number and that differ become charged. An atom that has lost or
in nucleon numbers (mass numbers) due to gained one or more electrons is called an
different numbers of neutrons in their nuclei. ion.
 Finding Number of Protons, Electrons and Neutrons
Element Nuclear Atomic Mass Number of Number of Number of
Symbol Number Number Protons Neutrons Electrons

Magnesium

Carbon

Potassium

Chlorine

Aluminium
Changing in Electron number
Changing in Proton Number
Changing in Neutron Number
Periodic Table
 Metals , Non-Metals and Metalloids

Metals Non-Metals
➢ solid (with the exception of mercury, Hg, a liquid). ➢ the elements to the right of the line are
➢ shiny, good conductors of electricity and heat. classified as nonmetals (along with hydrogen).
➢ ductile (they can be drawn into thin wires). ➢ The nonmetals are brittle, not malleable or
➢ malleable (they can be easily hammered into very ductile, poor conductors of both heat and
thin sheets). electricity, and tend to gain electrons in
➢ All these metals tend to lose electrons easily. chemical reactions.
Metalloids
The elements that border the stair-stepped line are classified as metalloids. The
metalloids, or semimetals, have properties that are somewhat of a cross between metals
and nonmetals.
Relative atomic mass vs Mass number?

Chlorine appears to have a mass number of 35.5. If

you calculate the number
of neutrons for chlorine you obtain:
number of neutrons = 35.5 – 17 = 18.5
It is not possible to have half a neutron and so there
must be something wrong
with this. The number 35.5 is not actually the mass
number for chlorine but
rather the relative atomic mass (Ar). Chlorine
consists of two isotopes, 35Cl
and 37Cl, and a naturally occurring sample contains a
mixture of these.
12
6𝐶 (98.99%)
13
6𝐶 (1.11%)
14
6𝐶 (~10-14 )
electronic structure of elements 1-20
Electron Distributions Into Shells for the First Three Periods
 Molecules and Chemical Bond
✓ Molecules
A molecule is a group of two or more atoms held together by attractive forces
known as chemical bonds.

An ionic bond Electrons in a Metallic bond is a term used to

essentially donates an covalent bond are describe the collective sharing
electron to the other shared equally of a sea of valence electrons
atom participating in between the between several positively
the bond. atoms. charged metal ions.
Metallic Bond
 Properties of
Matter

Physical Properties Chemical Properties

•mass •permeability •flammability •pH

•volume •ductility •toxicity •half-life
•density •pressure •enthalpy of formation •surface tension
•color •viscosity •heat of combustion •reactivity
•temperature •strength •oxidation states •hygroscopy
•melting point •solubility
•boiling point •opacity
•elasticity •Hardness
 States of Matter
Solid
A solid has a fixed shape and volume. The molecules in a solid have a regular, ordered
arrangement and vibrate in place but are unable to move far.
• diamonds (carbon atoms)
• ice (water molecules)
• metal alloys (mixtures of different metals)

The molecules in a liquid are not ordered and

can move from one region to another through
a process called diffusion.
Liquids
Liquids flow, and their density (mass per unit volume) is usually lower than the
density of solids. Liquids have a fixed volume but take the shape of the
container they are in.
• mercury (mercury atoms)
• vinegar (molecules of acetic acid)
• perfume (a mixture of liquids made of different molecules)
Gases
Gases take the shape and volume of the container they are in and can be
compressed when pressure is applied. The molecules in gases are disordered
and move quickly. The density of gas is much lower than the density of a liquid.
• helium gas (helium atoms)
• water vapor (molecules of water)
• air (mixture of different molecules, including nitrogen, oxygen, carbon
dioxide, and water vapor)
The arrangement of the particles in solids, liquids and gases
quite close
together and move far apart and move
regular, ordered with random rapidly in all directions
arrangement motion

The size and mass of a substance can change,

but its density (at a particular temperature) will
always remain constant regardless of the size.
 Six distinct changes of Phase
There are six distinct changes of phase that happen to different substances at different
temperatures:

# Note: Phase change is a physical process. No chemical bonds are formed or broken. Only the
intermolecular (physical) forces are affected.
 Absorbing Heat or Releasing Heat
• Freezing—A substance changes from a liquid to a solid.

• Melting—A substance changes from a solid to a liquid.

• Condensation—A substance changes from a gas to a liquid.

• Evaporation or vaporization— A substance changes from a liquid to

a gas.

• Sublimation—A substance changes directly from a solid to a gas

without
going through the liquid state.

• Deposition—A substance changes directly from a gas to a solid

without
going through the liquid state.
 What is Plasma?
Plasma is not a common state of matter here on Earth, but it may be the most
common state of matter in the universe.

Plasma consists of highly charged particles with extremely high kinetic energy.
The noble gases (helium, neon, argon, krypton, xenon and radon) are often used to
make glowing signs by using electricity to ionize them to the plasma state.

A plasma ball — also sometimes called a plasma

globe, lamp or sphere — is a clear glass ball filled
with a mixture of noble gases with a high-
voltage electrode at its center. Plasma filaments
extend from the electrode to the glass when
electricity is supplied, creating fascinating beams
of colored light.
Practice
1. Which of the following would NOT be considered a physical property?
a. flammability
b. hardness
c. solubilty
d. density
2. The smallest unit of matter is the
a. compound.
b. atom.
c. molecule.
d. proton.
3. Which is an example of a phase change?
a. oil floating on water
b. oxygen diffusing in water
c. paper burning
d. water freezing
Extra Practice-1
Extra Practice-2
Extra Practice-3
Change of phase is a process whereby matter changes form (solid, liquid, gas). Which
one of the following constitutes a phase change?
• A). condensation of water vapor
• B). photosynthesis
• C). digestion of food
• D). dry-cleaning
• E). exhaling
Extra Practice-4
What always stays the same when a chemical reaction takes place?
• A). the number of atoms
• B). the number of molecules
• C). the amount of gas
• D). the amount of solid matter
• E). the amount of disorder
 Physical and Chemical Properties
Extra Practice-5
Directions: Choose the best answer for each of the following items.
1. Complete the statement with the appropriate number answer.
The density of a metal with a volume of 30 milliliters and a mass
of 120 kilograms is ________________.

Extra Practice-6
The table gives the arrangement of in the atoms of four different element. Which
element does not form an ionic compound with chlorine?

3. GED Science (Chemistry-Matter)

 Extra Practice-7
Ice floats on water because
• A). ice is less dense than water
• B). water conducts heat better than ice
• C). ice has a lower temperature
• D). heat from the Earth’s core travels upward, cooling the bottom first.
• E). it needs energy from the sun to melt.

Extra Practice-8
Which of the following physical changes involve adding heat to a substance?
A. melting and boiling
B. boiling and condensing
C. condensing and freezing
D. evaporating and condensing

3. GED Science (Chemistry-Matter)

Extra Practice-9

Which is an example of a phase change?

a. oil floating on water
b. oxygen diffusing in water
c. paper burning
d. water freezing

Extra Practice-10
Which of the following is NOT a property of a gas?
A. no definite shape
B. can be compressed
C. definite volume
D. definite mass

3. GED Science (Chemistry-Matter)

Extra Practice-11
In warm, humid weather, people who wear glasses experience a very common effect
of phase change while getting off an air-conditioned bus: their glasses suddenly fog
up. After a while, the glasses become clear again. Which of the following physical
processes are involved in these phenomena?
A. condensation followed by evaporation
B. condensation followed by fusion
C. solidification followed by evaporation
D. solidification followed by fusion

4. GED Science (Chemistry-Chemical Reaction)

Extra Practice-12
Physical properties—A physical property is an aspect of a substance that can be observed
or measured without changing the identity of the substance.
Chemical properties—A chemical property is an aspect of a substance that can be
observed only during a chemical reaction that alters the substance’s chemical identity and
produces one or more new substances. Chemical and physical properties are thus related
to chemical and physical changes of matter.
Indicate the correct box where each of the following belongs.
• Molecular weight
• Oxidation
• Temperature
• Melting point
• Momentum
• Acidity
• Rusting

3. GED Science (Chemistry-Matter)

Wishing you to

With high marks