Chapter 2

Chemical Concepts

Objective

PS. 3 The student will classify matter according to its composition

PS.14 The student will infer the nature of matter

1. Composition of matter

1. Chemistry is the study of matter and its changes

1. matter is anything that has mass, volume, and inertia

1. mass is the amount of matter an object contains
2. volume is the amount of space an object takes up
3. inertial is the tendency for an object to resist change in motion

2. matter is made up of atoms
3. atoms are made up of subatomic particles

1. protons
2. neutrons
3. electrons

4. Matter can be divided into several categories

1. heterogeneous-

1. not the same throughout
2. all are mixtures

2. homogeneous-

1. even composition
2. are either

1. pure substances

1. elements found on periodic table
2. compounds- usually end in ide, ite, ate, or acid

2. or solutions- are a type of mixture

1. are made up of two parts

1. solvent-what does the dissolving
2. solute- what gets dissolved

2. Water is the universal solvent
3. Alloys are solutions made up of solids

1. bronze- copper and tin
2. brass- copper and zinc
3. stainless steel
4. 14K gold
5. chrome
6. sterling silver

Objectives:

PS.5 The student will differentiate between physical and chemical changes.

2. Changes in Matter- three types

1. chemical change

1. involves a change in the identity of the substance
2. a new material is formed
3. caused by a chemical reaction

1. is a breaking of bonds
2. evidence of a chemical change

1. Color change
2. Gas produced
3. Precipitate- a solid is produced
4. Light
5. Electric current produced
6. Heat given off or taken in

4. Represented by Chemical equations

1. that use formulas and symbols
2. starts with reactants and ends with products

5. Four main types of reactions

1. Synthesis or composition reactions- two or more reactants form one product C + O à CO
2. Decomposition reaction- one reactant breaks down into two or more products. ZnCl₂ à Zn + Cl₂
3. Single displacement reactions-one element replaces another in a compound. BeF₂ + Mg à MgF₂ + Be
4. Double displacement reactions- two compounds react to form two new compounds HCl + KOH à KCl + H₂O

6. Some common chemical reaction

1. combustion a reaction between methane and oxygen
2. Rusting- reaction between a metal and oxygen
3. Neutralization- reaction between an acid and base
4. Fermentation- the breakdown of sugars by yeast

7. In a reaction Mass is always conserved

1. conservation of Matter- matter is neither created or destroyed
2. Equations must be balances-

1. Coefficients number in the front
2. subscripts number at bottom

2. physical change

1. are changes in

1. size
2. shape
3. phase

1. solid
2. liquid
3. gas
4. plasma- exist in stars

2. caused by change in Kinetic energy- or the motion of the particles

1. types of changes

1. melting- form a solid to a liquid
2. freezing- form a liquid to a solid
3. vaporization- a liquid to a gas

1. evaporation is under normal conditions
2. boiling causes a liquid to vaporize not evaporate.

1. Boiling occurs when the vapor temperature at which the vapor pressure equals the atmospheric pressure on its surface.
2. altitude can change the boiling pt.

4. Condensation- a gas to a liquid
5. sublimation- for a solid to a gas without first changing to a liquid

3. nuclear change- deals with radiation and release of alpha, beta, or gamma particles

Objective

PS.2 The student will recognize that all matter is composed of molecules, atoms, or ions.

3. Types of particles

1. Atom is the smallest particle of matter
2. atoms combine to make compounds
3. compounds

1. are held together by chemical bonds
2. there are two types of chemical bonds

1. Covalent-

1. between two non-metals
2. a sharing of electrons to reach octet

2. Ionic

1. between a metal and a non-metal
2. a transfer of electrons
3. held together by the attraction between ions

1. Cation- positive
2. Anion- negative

Objectives

PS.6 The student will apply principles of the atomic theory of matter.

4. Atomic Theory

1. Atoms are the smallest particle of an element

1. has two main parts

1. nucleus- which contains the subatomic particles

1. protons- positive charge and identifies the atom
2. neutrons- no charge and gives the atom its mass

2. Electron cloud – which contains the

1. electrons- negative charge
2. used in bonding

2. Mass number

1. the number of protons and neutrons
2. the bigger number in each box on the periodic table
3. the same atom can have different mass numbers these are called Isotopes

3. Atomic number

1. the number of protons
2. the number of electrons in an atom with no charge
3. the small number in each box on the periodic table

4. Neutrons

1. to determine the number of neutrons
2. subtract the mass number minus the atomic number
3. the big minus the little

Objective

PS.11 The student will apply the periodic law to describe the relationship of elements.

5. Periodicity of elements

1. about 112 known elements
2. table created by Dmitiri Mendeleev
3. Arrangement

1. by increasing atomic number
2. by groups and periods

1. groups are vertical columns also called families
2. periods are horizontal rows that tell the number of energy levels

3. type of elements

1. Metals- conduct electricity and heat

1. alkali metal
2. alkaline earth metals
3. transition metals
4. rare earth metals

1. lanthanides
2. actinides

2. Metalloids-

1. contains properties of both metals and non-metals
2. called semiconductors
3. border the zigzag line

3. non-metals- do not conduct electricity and heat

1. Halogens- the most reactive nonmetals
2. Noble gases- usually do not react

Objective

CI.17 The student will distinguish common acids and bases.

CI.20 The student will develop, explain, and use the concept of pH.

6. Acids, Bases and pH

1. Acids

1. taste sour
2. turn blue litmus paper red
3. have a ph less than 7 (1-6)
4. contain a hydrogen (H) in the formula
5. Common acids

1. vinegar
2. citrus fruits
3. tomatoes
4. tea
5. carbonated drinks

2. Bases

1. feel slippery
2. turn red litmus paper blue.
3. a pH greater than 7 (8-14)
4. produce (OH^-) hydroxide ions in water
5. common bases

1. soap
2. shampoo
3. lye
4. window cleaner
5. drain cleaner
6. antacids

3. Acids and bases combine in a NEUTRALIZATION reaction
4. pH scale

1. the pH of pure water is 7
2. pH greater than 7 base
3. pH less than 7 acid 

Objective

PS.7 The student will interpret consequences of radioactivity

7. Radioactivity

1. Nuclear changes can occur in three ways

1. nuclear fission

1. occurs when a nucleus splits
2. a nuclear chain reaction is one in which once it starts it keeps going. Getting bigger and bigger
3. Used in nuclear power plants

2. nuclear fusion

1. the combination of two hydrogen nucleus to make a single helium nucleus
2. occurs in the sun and stars
3. do have a fusion bomb which is started by a fission bomb

3. radioactive decay

1. the normal process of an atom splitting
2. produces three types of radiation

1. alpha-

1. a helium nucleus
2. the weakest
3. stopped by skin, clothes

2. Beta particle

1. an electron
2. stronger than an alpha but not the strongest
3. stopped by large book, or a metal sheet

3. Gamma ray

1. a form of electromagnetic energy
2. the strongest form of radiation
3. can penetrate several feet of concrete

2. half-life

1. defined as the time it takes for half the mass to undergo radioactive decay.
2. Can be a few seconds to millions of years
3. Table