Power Point 4: Atoms, Molecules, & Ions
Drill: Calculate the volume in mL of a 2.0 m by 500.0 mm by 4.00 x 105 mm container.
(1 cm3 = 1 mL)
Atomic Theory: Elements composed of atoms. Atoms can’t be changed. Compounds comtain
multiples of atoms. John Dalton
The Law of Conservation of Mass: In ordinary chemical reactions, matter can be neither
created nor destroyed.
The Law of Constant Composition: Compounds always have the same proportions of the
elements within them.
The Law of 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.
•
Nuclear Atom: Proved by Rutherford & Bohr in the famous gold foil experiments
Atomic Composition:
•
Proton : in the nucleus (mass~ 1amu) (Charge = +1)
•
Neutron: in the nucleus (mass~ 1amu) (Charge = 0)
•
Electron: outside the nucleus (mass~ 1/1836amu) (Charge = -1)
•
Determined by Robert Milliken in the famous oil droplet experiment
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
AX
4
2He
Isotopes: Atoms that contain the same number of protons, but different number of neutrons
(Z constant, A variable)
Periodic Table: Graphic representation of all the elements indicating size, charge, electronic
structure, & reactivity (Elements have symbols with 1 upper case letter & maybe a 2nd letter)
•
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: Elements along the stair-stepped line from B to At. They share properties of
metals & nonmetals.
Compounds: A group of atoms that are chemically combined.
Molecule: A covalent compound that can exist by itself.
Drill: Convert: 1) 23 cm/ms to km/ns
2) 6 mg/nL to kg/ML
Atomic Mass: The weighted average mass of all the isotopes of an element. (an average of
relative abundance x mass number for each isotope)
Ions: Charges particles. (Cl-1) (OH-1)
Polyatomic Ion: A group of atoms chemically combined that together has a charge
(SO4-2 ) (NO3-1)
Chemical Formulas: Formulas that shows the number and kinds of atoms in a compound
(CaCO3)
Molecular Formula: A formula that shows the exact number and kinds of atoms in a molecule
•
C6H12O6
Binary Compound: A compound made up of two elements in any ratio. (NaCl) (Mg3P2)
Diatomic Molecules: Molecules made up of wo atoms of the same element that are chemically
combined. (Cl2, F2, O2)
Atomic Structure Problem: List & describe the three subatomic particles.
Atomic Structure Problem: Fill in the chart:
•
Isotope protons neutrons electrons
•
U-235
-
-
-
•
-
56
80
-
•
-
-
14
13
Determine the number of atoms in each compound:
C6H12O6
NaNO3
H3PO4
Al2(SO4)3
Problems:
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:
(5.00 % Pu-242) (5.00 % Pu-243) (80.00 % Pu-244) (10.00 % Pu-245)