Chemistry Review

Review Video... It’s a long one

Atomic Models1. Democritus: Indivisible piece of matter called the

atom2. Dalton: Elements made of atoms all alike &

compounds made of 2+ elements3. Thomson: Discovered electrons, atoms divisible,

pudding model4. Rutherford: Protons in nucleus, electrons

scattered around outside5. Bohr: electrons move in orbits around nucleus,

strongest ones far away from nucleus6. Wave: small positive nucleus surrounded by

electrons (same # as protons)

Structure of the atom

• Nucleus: (core) contains 99.9% of the mass of the atom, Contains protons and neutrons

• Protons: Positively charged particle. They are identical in every element

• Neutrons: Have no charge, identical in every element, differing numbers in the same element are called isotopes

• Protons and neutrons are made of smaller particles called quarks

Electrons

• Electrons whirl around the nucleus in the electron cloud

• Their mass is smaller than a proton or neutron

• They have a negative charge• The number of electrons an atom has

determines its chemical properties• Electron in outer level are called valence

electrons

Energy Levels

• 1st 2 electrons2nd 8 electrons3rd 18 electrons4th 32 electrons

• The further away from the nucleus, the more energy it has

Be happy its not you!

Atomic Number and Mass

• The number of protons in the nucleus determines the atomic number of the element

• The mass number is the sum of the protons and neutrons and is used to distinguish one isotope from another

• Atomic mass is the average mass of all the isotopes of an element

Forces in the atom

1. Electromagnetic force: Keeps the electrons spinning around the nucleus due to the repulsion/attraction

2. Strong Force: The greatest of the four forces3. Weak Force: Responsible for radioactive decay

through fusion4. Gravity: Force of attraction between objects,

weakest force

Nuclear Stability

Characteristics of Chemical Reactions

• Formation of a NEW substance, not the original substance

• Reactant: substance that enters into the reaction (original substance)

• Product: substance that is produced by a chemical reaction (new substance)

• The Law of Conservation of Mass states that mass remains constant in a chemical reaction

Bonding

• If an atom has 8 valence electrons it is stable and will not bond

• An atom with less than 8 valence electrons is unstable and will bond readily (easily)

• The ability to bond determines its ability to undergo chemical reactions

Reaction video

Balancing Equations

• Subscripts, symbols, and formulas cannot be changed because you would be changing the substance altogether.

• Coefficients can be added.• Balance the number of atoms of each element on

both sides to show that no mass has been lost or gained

Vocabulary

1. Exothermic: Heat, or energy, comes out of, or is released (gets hot), combustion

2. Endothermic: Heat, or energy, goes into (gets cold), reaction is the form of heat or light

3. Kinetics: the study of reaction rates

4. Collision Theory: The rate of a reaction is affected by concentration, surface area, temperature and catalysts

Periodic Table

Periodic Table• Dmitri Mendeleev Organized by atomic mass

(weight)• Henry Moseley, arranged the elements according

to their atomic numberGroups / Families

• Groups or families• They have similar properties• Vertical• They have the same number of valence electrons• There are 18 families… be able to name them!!• A,AE,T,B,C,N,O,H,NG

Families

1. Alkali Metal Family: most reactive metals, violent reaction in water

2. Halogen Family: most reactive nonmetals

3. Noble Gas Family: normally unreactive

Periods/ Rows

• Elements are not alike in the rows• First element in a row is an extremely active solid,

last is always an inactive gas• There are 7 periods• The number of the row they are in tells you the

number of energy levels• Horizontal

Element stuff you need to know

1. Hydrogen is a non-metal

2. Mercury is the only metal in liquid form at room temperature

3. Most of the elements are metals in solid form

4. The non-metals are in gas form

5. There are only a few metalloids along the zig-zag line

6. Radioactive elements are mostly man-made

Position on the table

Bonding

1, 2, 3 = lose electrons5,6,7 = gain electrons4 = gain or lose8 = unresponsive1. Ionic bonding – involves a transfer of electrons.

One atom gains and the other one loses (metal and non-metal)

2. Covalent bonding –They share electrons, rather than transfer. (Non-metal and non-metal), from molecules

3. Metallic bonding: metal and metal, electrons are able to fly off the energy levels

Dumb Criminals

Vocabulary• Chemical bonding – the combining of atoms of elements to

form new substances• Ion – a charged atom (positive or negative).• Ionization – the process of removing electrons to form ions. • The energy needed is called ionization energy.• Electron affinity – the tendency of an atom to attract

electrons.• Polyatomic ion – when two elements bond first covalently

then through ionic bonding• Oxidation number – the number of electrons an atom gains

or loses, or shares in a chemical bond.• Diatomic elements – form bonds with atoms of the same

element.

Radioactivity

1. Becquerel: Provided evidence of x-rays and Uranium

2. Curie: discovered Radioactive Elements, Polonium and Radium

3. Rutherford: Produced the first artificial transmutation

Particles

1. Alpha: Nucleus of He atom, Weakest, Positive charge, stopped by paper

2. Beta: Electron formed in the nucleus when a neutron breaks apart, pass through 3 mm of aluminum

3. Gamma: Electromagnetic wave of high frequency and short wave length, Strongest, Can pass through lead

Mutation??

Fission and Fusion

Vocabulary1. Binding energy: needed for the stability of a nucleus2. Radioactive decay: The spontaneous breakdown of

an unstable atomic nucleus3. Decay Series: The series of steps by which a

radioactive nucleus decays into a non-radioactive nucleus.

4. Alpha Decay: Occurs when a nucleus releases an alpha particle

5. Beta Decay: Loses a beta particle causing the # of protons to go up by 1.

6. Gamma Decay: Release of gamma ray, Nucleus is not changed only lowered to a different energy level

7. Transmutation: Where one element changes into another as a result of changes in the nucleus (beta decay)

8. Radioactive Half-Life: The amount of time it takes the atoms in a given sample of an element to decay

9. Particle accelerator uses magnets and electric fields to speed up particles

10. Fission: Splitting of an atomic nucleus into 2 smaller nuclei of approximately equal mass, I Break, power plants

11. Fusion: Joining of 2 atomic nuclei of smaller mass to form a single nucleus of a larger mass, U Make, sun and atomic bombs