The Periodic Table of Elements and Atom Types

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The Periodic Table of Elements and Atom Types

• I. Organization of the Periodic Table

A. periodic law properties of elements tend
to change in a regular pattern when elements are
arranged in order of increasing atomic number.
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• B. Elements are arranged in periods and groups

1. period a horizontal row of the
elements in the periodic table
a. another name for periods are valences
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• 2. Every atom has valence electrons
• a. Electrons are arranged in energy levels.

i. Each energy level can hold only a specific
number of electrons ii. Electrons start at the
energy level closest to the nucleus and fill up
one energy level after another.
b. valence electron an electron
in the outermost energy level of an atom
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• B. Elements are arranged in periods and groups

1. period a horizontal row of the
elements in the periodic table
a. Another name for periods are rows
b. Each period has a number, which refers to how
many energy levels are in that element.

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2. group (family) a vertical column of the
elements in the periodic table
a. Groups of elements in the periodic table,
have similar properties
b. Valence electrons largely effect chemical and
physical properties.
c. Elements in the same group have the same
number of valence electrons.
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• II. Ions!!!

A. Ion an atom that has lost or gained one or
more electrons and therefore has a net electric
charge.
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• E. Atoms have no overall charge
• 1. An un-reacted, elemental atom has the same
  number of protons as electrons
• 2. Each proton has 1 positive charge and each
  electron has 1 negative charge.
• 3. Positive charges and negative charges cancel
  each other out.

2 protons 2 charges 2
neutrons 0 charge 2 electrons
- 2 charges
0 charge
7 protons 7 charges 7
neutrons 0 charge 7 electrons
- 7 charges
0 charge
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• II. Ions!!!

A. Ion an atom that has lost or gained one or
more electrons and therefore has a net electric
charge.
B. Ionization the process of adding or
losing one or more electrons from an atom
C. Atoms want all of their energy levels to be
full. Adding or losing electrons helps
this to happen.
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• C. Ions have charge!

1. cation an ion that has given up one or
more electrons
17 protons 17 charges 18
neutrons 0 charge 18 electrons
- 18 charges
- 1 charge
a. Cations have more protons than electrons.
b. Cations have an overall positive charge.
2. anion an ion that has gained one or more
electrons
a. Anions have fewer protons than electrons.
11 protons 11 charges 12
neutrons 0 charge 10 electrons
- 10 charges
1 charge
b. Anions have an overall negative charge.
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III. Differences in atomic structure

• A. Atomic number

1. atomic number the number of protons in an
atom
2. Each element has its own atomic number.
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• B. Atomic mass

1. atomic mass the mass of an atom of a given
element
2. The average atomic mass is never a whole
number.
C. Isotopes!!
1. isotopes any atoms having the same number of
protons but different numbers of neutrons
C
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2. average atomic mass the mass of the average
atom of a given element
a. Atomic mass unit (amu) a unit equivalent to
1/12 the mass of a carbon- 12 atom (1 proton or
neutron)
b. It reflects number of protons and neutrons in
naturally occurring elements.
12 protons 12 neutrons 24 amu
12 protons 13 neutrons 25 amu
12 protons 14 neutrons 26 amu
78.65 x 24 amu 10.14 x 25 amu
11.13 x 26 amu 24.305 amu