Chemistry
THE PERIODIC TABLE
Periodic Table
 Group – Vertical columns on PT
 Period – Horizontal rows on PT
Main-Group Elements
 Groups 1, 2, and 13-18
Main-Group Elements
 The chemical properties of the main-
group elements depends on their
number of valence electrons
 Valence electrons are the outermost
electrons involved in chemical
bonding
Valence Electrons & Chemical
Properties
 Each group of the main-group
elements has the same number of
valence electrons
 Each element wants to be as stable
as possible
 All main-group elements want a full
shell of electrons, which is 8 valence
electrons
Valence Electrons & Chemical
Properties
 Each group forms ions based on the
easiest way to obtain this full shell
 Also known as the octet rule
Family Groups
 Noble Gases (Group 18)
 Examples: Ne, Xe
 Description: stable,
unreactive group of
gases
 Number of Valence
Electrons: 8
 Forms NO ions
Family Groups
 Halogens (Group 17)
 Examples: F, Cl
 Description: Highly reactive group
of gases
 Number of Valence Electrons: 7
 Forms 1- ions
Family Groups
 Alkali Metals (Group 1)
 Examples: Na, K (not H)
 Description: Highly reactive group
of metals
 Number of Valence Electrons: 1
 Forms 1+ ions
Brainiac Movie
Family Groups
 Alkaline-Earth Metals (Group 2)
 Examples: Be, Mg
 Description: Slightly less reactive group than alkali
metals
 Number of Valence Electrons: 2
 Forms 2+ ions
Family Groups
 Transition Metals (Group 3 – 12)
 Examples: Fe, Au, Ag
 Description: Fairly stable group of metals
 Forms multiple ions
Family Groups
 Lanthanides & Actinides
 Location: Bottom 2 periods of PT
 Description: Heavy metals, synthetics, radioactive
States of Matter
 Metals and Nonmetals (Staircase)
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TRENDS OUTLINED
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Periodic Table Trends
 Atomic Size
 Definition: The volume occupied by the
electrons around a nucleus
 Period Trend
 Caused by: Increasing Effective Nuclear
Charge
Atomic Size
 Effective nuclear charge is the
amount of charge felt by outer
electrons in an atom
 Group trend
 Caused by: Increasing electron energy levels
Ionization Energy
 Definition: The amount of energy required
to remove one electron
 Period trend
 Caused by: Inc. Effective Nuclear Charge
Ionization Energy
 Group trend
 Caused by: Electron shielding
 Electron shielding occurs when inner electrons
shield outer electrons from the pull of the
nucleus
Electron Affinity
 Definition: The attraction of an atom
for an electron
 Period Trend
 Caused by: Inc. Eff. Nuclear Charge
Electron Affinity
 Group trend
 Caused by: Inc. electron shielding
Electronegativity
 Definition: How much an atom in a
chemical bond attracts electrons
 Period trend
 Caused by: Inc. Eff. Nuclear Charge
Electronegativity
 Group trend
 Caused by: Electron
shielding/Inc. electron energy
levels
Effective Nuclear Charge
Electron energy levels
Electron shielding
Filling Electron Orbitals
 Orbitals are the area in space
where electrons are found
 Each individual orbital holds 2
electrons
 There are four main shapes
which hold a different number
of electrons
Shapes of Orbitals
 The four shapes are s, p, d, and
f
Shapes of the Orbitals
 Each shape holds a
different number of
orbitals
 s has 1 orbital, p has 3 orbitals,
and d has 5 orbitals
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Energy Levels
 Each period is a
new energy
level
 Like an
elevator,
electrons
cannot exist
between
energy levels!
General Rules
 Aufbau Principle – Electrons fill lowest energy
level first
 Analogy: Lazy Tenant Rule
General Rules
 Pauli Exclusion Principle – Electrons must
have opposite spin (up/down) when in the
same orbital
 Analogy: Yin and Yang Rule
General Rules
 Hund’s Rule – Electrons in equal energy
orbits fill orbitals with parallel spin
 Analogy: Empty Bus Seat Rule
Orbital Notation
 Specific order for filling electrons – based on
periodic table
 Examples
 Beryllium
 Oxygen
Orbital Notation
 Examples
 O2-
 Titanium
Electron Configuration
 Examples
 Silicon
 Selenium
 Manganese
Shorthand Electron Config
 Shorter version of
writing electron
configurations
 Noble Gas Core –
inner core of
electrons not
involved in
chemical bonding
Shorthand Electron Config