Goal 4 EOG REVIEW
The learner will conduct investigations
and utilize technology and information
systems to build an understanding of
chemistry.
Identifying Chemicals
• Chemical: a substance used in or formed
by a chemical process. It is also any
substance with definite composition
(meaning it is always made up of the same
substances). For example, water will
always be made up of one part oxygen
and two parts of hydrogen.
• We have two categories for chemicals:
natural and synthetic.
Con’t
• Natural chemicals: exist in nature
ex.
Water, air
• Synthetic chemicals: not naturally occurring, and
is made in laboratories by people. Ex. Steel
and bronze, medicines
• Matter: anything that has mass and volume.
• Mass: the amount of matter in a substance.
• Volume: the amount of space the substance
occupies.
Con’t
• Three states of matter:
– Solid: has definite shape and volume
– Liquid: has a definite volume but not shape
– Gas: has neither a definite shape or volume
• Elements: a substance that cannot be broken
down into simpler substances. Ex. Hydrogen,
oxygen, carbon
• We have 109 known elements on the periodic
chart that have been discovered by man.
Con’t
• Of the 109 known elements, 92 are naturally occurring.
• Elements can combine in different ways to form mixtures
or compounds.
– Mixture: a type of matter that forms when two or more
substances are combined but do not chemically join. Ex. Cereal,
air
– Compound: a type of matter that forms when two or more
elements combine CHEMICALLY. This will form a new
substance different than the original reactants. Ex. Na
combining with Cl will give you table salt. Na starts out as a
metal and Cl is a poisonous gas, but when you combine them
you get table salt.
Elements Form Compounds
• Compounds have 3 important characteristics:
– A definite composition
– Can be broken down into simpler substances by
chemical means
– Can be identified by their physical properties
• Molecule: the smallest unit of a compound that
has all the properties of the compound. We
represent the make-up of a molecule in a
chemical formula.
– Chemical formula: chemical symbols and subscripts
that identify the number of atoms of each element in a
molecule of a compound.
Con’t
– Ex. Chemical formula for water is H O.
2
• Atoms: the smallest unit of an element that has
all the properties of the element. They are the
building blocks of matter.
• Atoms are made up of three types of particles:
– Protons: have a positive charge and reside in the
nucleus
– Neutrons: have a neutral (or no) charge and also
reside in the nucleus
– Electrons: have a negative charge and reside in the
electron cloud (energy levels)
Con’t
• For more on atoms go to
http://education.jlab.org/atomtour/
• http://www.school-forchampions.com/science/atom.html
• Each energy level of an atom can hold
only a specific number of electrons.
Con’t
Energy Level
1
Maximum Number of
Electrons
2
2
8
3
18
4
32
Con’t
• Valence electrons: the electrons in the
outermost energy level of an atom. These are
the electrons that participate in bonding.
• Chemical bonding: the exchange of electrons
that hold atoms together. There are two types:
ionic and covalent
– Ionic: When two atoms bond and one atoms loses
a(n) electron(s) and the other gains. For example,
when Na bonds with Cl, the Na will lose one electron
and the Cl will gain one electron.
Con’t
– Because they are bonded, both Na and Cl will
now have a full outside energy level.
– All atoms participate in bonding for one
reason only….to get a full outside energy
level.
– Atoms that are in groups 1, 2, and 3 will lose
their valence electrons. Atoms in groups 5, 6,
and 7 will gain valence electrons.
– Ionic bonds are formed by combining atoms
that are metal with ones that are nonmetal.
Con’t
– Covalent bonding: formed when two atoms share
valence electrons. This is also done to fill the outside
energy level with valence electrons. But in this kind,
no one loses or gains. Everyone shares.
• Happens between two nonmetals.
• Ex. 2 Hydrogens will share one electron each with
Oxygen to form water.
• Elements can combine in a multitude of different ways to
form many different substances. For example, H2O is
water but H2O2 is hydrogen peroxide.
Con’t
• Atomic theory:
– All matter is composed of atoms
– Atoms of a given element are identical
– Atoms of different elements combine in simple
whole-number rations to form chemical
compounds (this is why you can not have a
coefficient or subscript with a decimal).
• Compounds are found in both living and
nonliving things
The Periodic Table
• Mendeleev tried to find a way to organize
info about the known elements of his time.
• He wrote each element’s name and
properties on a separate card.
• He looked for a pattern in the properties of
the elements that could be used to
classify and keep info about them in an
organized way.
Con’t
• Periodic table: a chart that organizes info
about all of the known elements according
to their properties. It is organized by
atomic number.
• Atomic number: the number of protons
contained in the nucleus of the atom.
• Atomic mass: the number of protons plus
neutrons in the nucleus of one atom of the
element.
Con’t
• Period: the horizontal row in the periodic
table. There are 7 periods.
• Group or Family: the vertical columns on
the periodic table. There are 18 groups.
Group number determines the number of
valence electrons.
– For example, if you have an element from
Group 1 then the atom will have 1 valence
electron. The number of the group number =
the number of valence electrons.
Con’t
– But, for familys 11-18, you have to drop the
first digit of the family number. So, if you have
an element from group 17, then it will have 7
valence electrons.
• Reactivity: how likely an element is to form
bonds with other elements. The most
chemically active metals are group 1, and
they are called Alkali metals.
– Group 2 are called alkaline earth metals.
They are slightly less reactive than group 1.
Con’t
• Groups 3-12 are called the transition metals.
• Metalloids: elements that have some properties
of both metals and nonmetals. They fall along
the jagged line of the periodic table between the
metals and nonmetals.
• Group 17: Halogens, the are the most reactive
nonmetals.
• Group 18: Noble gases, they are the least
reactive of all elements because their outside
energy level is full.
– Inert: unable to react chemically.
Con’t
• Properties of Metals and Nonmetals
Metals
Nonmetals
Solid at room temp, except
Mercury
Malleable and ductile
Gases, except Bromine
Luster- shiny
Dull, not shiny or bright
Highly conductive- carry
electrical current
Poor conductors
Tend to lose electrons in
chemical reactions
Tend to gain electrons in
chemical reactions
Brittle
Websites
• http://www.chem4kids.com/files/elem_intro
.html
• http://www.chem4kids.com/files/elem_pert
http://www.chem4kids.com/files/elem_metal.html
able.html
• http://www.chem4kids.com/files/elem_fami
lies.html
• http://www.chem4kids.com/files/elem_met
al.html
Properties of Matter
• Property: any characteristic that can be
used to identify and describe matter.
– We have two types:
• Chemical: a characteristic that describes how the
matter will change under certain conditions. Ex.
Ability to burn, rust, react to light, or react with
acids.
• Physical: any characteristic of a substance that
can be observed without changing the identity of
the substance. Ex. Mass, volume, color, hardness,
and phase.
Con’t
• Metals: an element that is a good conductor of
electricity and heat, usually solid at room temp,
and is on the left-hand side of the periodic table.
About 75% of all elements are metals.
• Nonmetals: an element that does not readily
conduct electricity or heat, usually are gases at
room temp.
• Metalloids: an element that has some properties
of both metals and metalloids.
Con’t
• Malleability: able to be hammered and shaped
or rolled into thin sheets Ex. Gold can be
shaped into necklaces
• Ductility: can be stretched or drawn into wires
without breaking. Ex. Copper can be made into
wire.
• Magnetism: a force of attraction or repulsion
that exists between like or unlike poles. The
metals iron, cobalt, and nickel have strong
magnetic properties.
Con’t
• Conductor: a material or substance that
allows electrons to flow through it easily.
• Insulators: materials that do not allow
electricity to flow through them easily.
• Semiconductor: a material that has
conductive properties that are in between
conductors and insulators.
Con’t
• Density: the ratio of mass to volume
– D = mass/Volume
– The density of water is 1.0 g/mL
– When an object is more dense than the liquid
it is placed in, it will sink
– If is less dense, it will float.
• Solubility: a measure of how much of a
substance dissolves in a given amount of
another substance.
Con’t
• Substances can be identified by certain
properties.
– Physical properties:
• Density
• Melting point: the temp at which a solid changes to a liquid
• Boiling point: the temp at which gas bubbles form in a liquid
and rise to the surface and escape the liquid as gas.
• Specific heat: the amount of energy needed to raise 1 gram
of a substance by 1 degree Celsius. The lower the
substance’s specific heat, the faster that substance would
rise in temp when heated.
• Solubility: a measure of how much of a substance dissolved
in a given amount of another substance.
Con’t
• Solutions: a mixture in which the particles
are too small to be distinguished from
each other and remain constantly and
uniformly mixed.
– Made up of solute and solvent
• Solute: the solid that gets dissolved
• Solvent: the liquid that dissolves the solute
• Example: To make Koolaid, sugar and Koolaid
flavoring are the solute that dissolves in water (the
solvent).
Con’t
• Substances can also be identified by
chemical properties like reactivity.
– Reactivity: how likely an element is to form
bonds with other elements.
Measuring Physical and Chemical
Changes
• Physical change: alters the physical
properties of a substance without altering
the identity of the substance. For
example, melting ice, tearing a sheet of
paper, and sharpening a pencil.
• Chemical change: occurs when a
substance is changed into a new
substance with different properties.
Con’t
• A chemical change involves a chemical
reaction.
– Chemical reaction: the process by which new
substances are formed. You can not usually
reverse the effects of a chemical change.
– Evidence of chemical change: formation of a
precipitate (a solid that forms from a chemical
reaction that takes place in a solution), gas
formation, color change, and energy change.
Con’t
• During a chemical reaction, chemical bonds are
either broken or formed. Energy is released
whenever new bonds from to join substances
together.
• A chemical reaction is represented by a
chemical equation.
– Propane + oxygen - carbon dioxide + water +
energy
– propane and oxygen are the reactants
– Carbon dioxide, water, and energy are the products.
– The whole thing is the chemical equation
Con’t
• Reactant: a substance that takes part in a
chemical reaction.
• Product: a substance formed during a
chemical reaction.
Conservation of matter
• The law of conservation of matter: states that during a
chemical reaction, matter can not be created or
destroyed. So mass does not change nor does the
number of atoms.
– For example, if you started out with 4 grams of Iron
and 3 grams of Oxygen, when they combine you
would have to have 7 grams of Iron oxide.
– Or if you had 8 Irons and 6 Oxygens before the
reaction you would have to have 8 Irons and 6
oxygens after the reaction. So, Fe8 + O6  2Fe4 O3
• For practice on balancing chemical
equations go to
– http://education.jlab.org/elementbalancing/ind
ex.html
– http://www.mpcfaculty.net/mark_bishop/balanc
ing_equations_tutorial.htm
Harmful Chemicals
• Your body comes in contact with many
different kinds of chemicals. Some are
good for you and some are not. Exposure
to harmful chemicals can cause cancer,
birth defects, autoimmune diseases,
diabetes, heart disease, kidney disease,
asthma, and learning or behavioral
disorders.
Con’t
• Cancer: a group of diseases caused by
abnormal cell growth and reproduction.
Chemicals that can cause cancer are
called carcinogens. Some known
carcinogens are cigarette smoke, tar,
carbon monoxide, nicotine, arsenic, and
cadmium, asbestos, and radon.
Con’t
• Chemical exposure can cause birth
defects. Birth defects are physical
abnormalities that show you in the child at
the time of birth of the child. This happens
because the mother was exposed to a
chemical during the pregnancy. Examples:
fetal alcohol syndrome, cleft lip, cleft heart
defects.
Con’t
• Chemicals can cause heart disease. In this
disease, the arteries that supply blood to the
heart are narrowed or blocked. Chemicals that
can cause heart disease are nicotine and
cholesterol.
• Chemicals can cause kidney disease. The
kidneys are the main organs of the urinary
system. They filter out waste products from the
blood. When you have kidney disease, your
kidneys can no longer filter the waste products
out efficiently.
Con’t
• Chemicals can cause asthma. A person
with asthma has difficulty breathing.
Effects of Chemicals on Organisms
• Chemicals are used in industry,
agriculture, and in our homes. Some are
helpful, and some are harmful to humans
and other organisms.
• Dose: the amount of a chemical
substance that is given to one individual.
• Potency: refers to how powerful the
chemical is.
Con’t
• Exposure time: how long an individual is
exposed to a chemical.
• Individual susceptibility: how each person
is going to respond to a chemical based
on the physical and genetic make-up of
that individual.
• Concentration: the amount of a substance
in a given volume.
Con’t
• How a person is going to react to a
chemical is going to be based on:
– Their individual susceptibility
– The concentration they receive
– The dose
– The potency
– And how long they were exposed to the
chemical.