Drill: Convert: 1) 23 cm/ms to km/ns 2) 56 mg/nL to kg/ML

Chapter 2 Atoms, Molecules, & Ions

Atomic Theory Elements composed of atoms Atoms can’t be changed Compounds of multiple atoms Originated with John Dalton

Conservation of Mass In ordinary chemical reactions, matter can be neither created nor destroyed

Constant Composition Compounds contain elements that are always in the same proportions

Multiple Proportions The elements making up a compound will form whole number ratios

Atom The smallest particle that an element can be broken down into and still maintain the properties of the element

Atomic Composition Proton: in the nucleus Neutron: in the nucleus Electron: outside the nucleus

Proton In Nucleus +1 charge About 1 amu in mass

Neutron In nucleus Neutral in charge Mass is about 1 amu

Electron Outside the nucleus -1 in charge Negligible mass about 1/2000 amu

Atomic Number The number of protons in an element Z number

Mass Number The number of protons and neutrons in an atom A - number

Nuclear Symbol Z 2 X He A 4

Isotopes Atoms that contain the same number of protons, but different number of neutrons Z constant, A variable

Atomic Mass The weighted average mass of all the isotopes of an element average of relative abundance x mass number for each isotope

Periodic Table Graphic representation of all the elements indicating size, charge, electronic structure, & reactivity

Rows which indicate energy level or shell or size of the atoms Periods Rows which indicate energy level or shell or size of the atoms

Groups or Families Columns which indicate the number of electrons in the outermost energy level determining charge & reactivity

Metals Left three quarters of the chart Lose electrons Become positive

Nonmetals Upper right portion Gain, lose, or share electrons when they react

Metalloids Along the stair-stepped line from B to At Share properties of metals & nonmetals

Radioactivity The spontaneous breakdown of an unstable nucleus

Radioactive Decay Alpha radiation Beta radiation Gamma radiation

A group of atoms that are chemically combined Compound A group of atoms that are chemically combined

Molecule A compound that can exist by itself

Two atoms of the same element that are chemically combined Diatomic Molecule Two atoms of the same element that are chemically combined Cl2, F2, O2

Ion Charged Particle Cl-1

Polyatomic Ion A group of atoms chemically combined that together has a charge SO4-2

Binary Compound A compound made up of two elements in any ratio NaCl Mg3P2

Chemical Formula A formula that shows the number and kinds of atoms in a compound CaCO3

Molecular Formula A formula that shows the number and kinds of atoms in a molecule C6H12O6

List & describe the three subatomic particles Atomic Structure List & describe the three subatomic particles

Atomic Structure Fill in the Chart: Isotope protons neutrons electrons - 56 80 - - - 14 13

Calculate the atomic mass of the element made up of the following isotopes: 99.50 % H-1 0.30 % H-2 0.20 % H-3

Calculate the atomic mass of the element made up of the following isotopes: 5.0 % Pu-242, 5.0 % Pu-243 80.0 % Pu-244, & 10.0 % Pu-245

Determine the number of atoms in each compound C6H12O6 NaNO3 H3PO4 Al2(SO4)3