Chapter 2

Dr. C.’s AP ChemistryLake Dallas High School

Fall 2014

Law of Conservation of Mass

• Mass is neither created nor destroyed in a chemical reaction (it just changes form)

– Burning of a candle

Law of Definite Proportion

• A given compound always contains exactly the same proportion of elements by mass

– H2O

Dalton’s Atomic Theory• Each element is made up of tiny particles called

atoms• The atoms of a given element are identical; the

atoms of different elements are different in some fundamental way

• Chemical compounds are formed when atoms of different elements combine with each other.

• Chemical reactions involve reorganization of the atoms (different bonding) but the atoms are not changed.

History of Atomic Theory

Modern Atomic Structure

• Nucleus (10-13 cm diameter)• Electrons (avg. distance 10-8 cm from nucleus)

• Nucleus contains:– Protons & Neutrons

• Nucleus accounts for almost all of the atoms mass.

• Number of electrons determines the chemical properties of an atom.

• The number of protons determines the identity of the atom

Practice

• Ca

• Fe

• Fe2+

• Br-

Groups/Families have similar chemical propertiesAtomic Radius increases down the groups

Isotopes

• Same number of protons, different number of neutrons.– Dalton’s assumption that all atoms of the same

element were identical in all their properties.

• Which Carbon isotope is the most common/abundant?

12C 13C 14C

Why?

Charges on Transition Metals

• PbCl2

• MnO2

• CuCl

** Charges must balance each other **

Polyatomic Ions (p. 65 in your book)

Naming Ionic CompoundsFrom Formula to Name

• Metal + Non-metal OR Metal + Polyatomic

• 1st Name the cation.– If the cation is a transition metal its charge must

be written in ( )’s.• 2nd Name the anion and change its ending to

-ideOR Write full name of the polyatomic anion

Practice

• CoBr2

• Al2O3

• CaCl2

Naming Ionic CompoundsFrom Name to Formula

• Metal + Non-metal OR Metal + Polyatomic

• 1st Write the symbol for the cation and its charge.

• 2nd Write the symbol for the anion and its charge

• 3rd Circle the charges and “cross” them to balance charges.

Practice

• Gallium Bromide

• Manganese (IV) Oxide

• Lead (II) Chloride

• Calcium hydroxide

Homework

Wednesday We Will Discuss Naming Covalent Compounds and Naming Acids

• Work on your journal article• Read pages 54 – 70• Start on Homework #2 (page 72- 80) 5, 12, 23, 24, 36, 42, 50, 56, 58, 64, 68, 72, 74, 76, 78, 80, 84, 86, 90, 94, 96, 98, 112, 120