Review Session

conversion

• Given that 1.00cm3= 1.00mL…

How many Kiloliters of water are in one million cm3???

Answer?= 1 kL

Conversion

• If you have 1000 yen how many euro do you have? (yen to dollar =0.0119, euro to dollar= 1.274)

Conversion

• If you run a 5.00 km marathon how many miles are you running? (1.609 km= 1 mile)

• Answer= 3.11 miles

Conversion Review

There are 4840 square yards in every acre. Since there are 1.196 square yards in every square meter, how many square meters are in 4 acres?

Predicting atomic structure from the Periodic table

• Atomic # is the number of protons

• Atomic mass is the sum of protons and neutrons

• # of electrons = # of protons in an atom

• # of electrons in ions is larger or smaller than number of protons by the opposite of the charge

Predicting Atomic Structure Review

Element Atomic #

Atomic Mass

Protons Neutrons Electrons

C 14

O2- 8

10 20 10

1 1

7 7 7

Matter

• Matter is a general term for all the substances in which all objects are made.

• Matter is divided into two categories:– Pure substances– Mixtures

Pure substances

• A pure substance can be defined as a sample of matter that consists of only one component with definite physical and chemical properties and a definite composition.– Pure substances cannot be broken down into

simpler substances by chemical means– Examples of a pure substance may be an element

or a compound

Pure Substances

Nitrogen

Carbon dioxide

• hydrogen

Mixtures

• a combination of two or more phases that are not chemically united and do not exist in fixed proportions to each other.– Basically two things are mixed together and can be

separated– Mixtures can be either heterogeneous (made of

two different compositions )or homogeneous (a mixture of the same composition)

Examples of mixtures

homogeneous• Air with no clouds• Sugar water• Salt water• Milk

heterogeneous• Gravel• Salt and pepper• Sand• Some salad dressings (Italian)

Review

• Which are pure subtances and which are mixtures?

• Lemonade• Helium gas• Soil• Deionized Water• Ammonia• Ceasar Dressing

Chemical vs. physical change

chemical• A change in the composition

of the elements in the compound.

• A microscopic change

physical• Difference in the way that

something looks• A different state of matter• If the solid is in solution or

not

Review questions

• What would you consider is the most common physical change in your daily life? What is the most common chemical change?

• If you burn food is that considered a physical change or a chemical change? Why or why not?

Review Questions

• As food is digested does it go through a physical change or a chemical change?

• When making Kool aid does a physical or chemical change take place

• What is happening to the atoms on a microscopic level in a physical change and in a chemical change?

History of the Atom

Review Session Tuesday Se

The Atomic Theory of Matter – Dalton’s Atomic Theory

•Each element is composed of extremely small particles

called atoms, or the smallest representative part

of an element

•Atoms in a given element are identical to each other

•Atoms of one element are different from all atoms in

other elements

•Compounds are formed when atoms of different

elements combine in whole number ratios

•A chemical change (reaction) involves rearrangement of

atoms BUT no atoms are created or destroyed

The Plum Pudding Model

•1897 – Discovery of the first subatomic particle, electrons

(negative)

• J.J. Thomson (1856-1940)

• led to the first model of an atom

•Atoms have no net charge, or a charge of zero

• Suggesting there has to be a positive charge (proton)

The Nuclear ModelErnest Rutherford (1871-1937)

• Found all of the positive charge was in a very small, very dense central area of the atom, he called the nucleus.

electron

neutron

proton

The Modern View of Atomic Structure

•There are three subatomic particles of an atom

Neutrons (neutral charge = 0), located in the nucleus

Protons (positive charge = +1.602 x1019 C), located in the

nucleus

Electrons (negative charge = -1.602 x1019 C), located in the

electron cloud around the nucleus

•Every atom has an equal number of electrons and protons creating

no net charge

Give it Some Thought:

•What are the three subatomic particles, their charge and

where are they located in an atom?

•When and what was the first subatomic particle founded?

•Define reaction.

•What is the charge on an atom?

•What is the modern view of an atom?

• Conversion Problem:

• Your company makes dresses, each dress requires 4 yards

of fabric, unfortunately your supplier only sells fabric by

the meter. How many meters of fabric do you need to

make 39 dresses? (1 yard = 0.9144 meters)

Bohr Contributions• Bohr established the idea of electrons being

restricted to certain energy levels that surround the nucleus

• This was based on a experimental observation that atoms only absorb and release specific energies when light energy is added

Modern Atomic Theory• The location of electrons in an atom is given in

terms of probably • This is because we can only predict where an

electron will be at a certain time• The location of highest probably is called an

orbital or electron cloud

Orbital Trends

• Orbitals that are closer to the nucleus have less energy than ones farther away

• Electrons can only occupy orbitals and certain energy levels Ex: n=1 or a d orbital

• Electrons can change energy levels if enough energy is added to the atom

Review Question• What idea did Bohr establish?• What experimental evidence did Bohr have to

support this idea?• What is the most probable area for an

electron to be located called?• Can we ever be sure where an electron is

located?• What kind of energy can be added in order to

change the orbital level of an atom?