Intro to Bonding
Valence Electrons,
Lewis Dot Structures,
and
Electronegativity
Standards
2. Biological, chemical, and physical properties of matter result from the ability of atoms to form bonds from
electrostatic forces between electrons and protons and between atoms and molecules. As a basis for
understanding this concept:
a. Students know atoms combine to form molecules by sharing electrons to form covalent or metallic bonds or
by exchanging electrons to form ionic bonds.
2. b. Students know chemical bonds between atoms in molecules such as H2, CH4, NH3, H2CCH2, N2, Cl2, and
many large biological molecules are covalent.
2. c. Students know salt crystals, such as NaCl, are repeating patterns of positive and negative ions held
together by electrostatic attraction.
2. d. Students know the atoms and molecules in liquids move in a random pattern relative to one another
because the intermolecular forces are too weak to hold the atoms or molecules in a solid form.
2. e. Students know how to draw Lewis dot structures.
2. f.* Students know how to predict the shape of simple molecules and their polarity from Lewis dot structures.
2. g.* Students know how electronegativity and ionization energy relate to bond formation.
2. h.* Students know how to identify solids and liquids held together by van der Waals forces or hydrogen
bonding and relate these forces to volatility and boiling/melting point temperatures.
The Hippie
The Hippie
Sure man, it’s only money. I’ll
probably be happier if I give it
away anyhow.
The Accountant
The Accountant
No Way am I giving you my Money!
You’re Irresponsible.
In fact give me your money so I can
invest it for you!
Electronegativity
• electronegativity – how much an atom wants
to keep hold of its electrons.
• ionization energy – the energy required to
remove an electron from an atom.
Greater
electronegativity
Lower
electronegativity
Which has the greater
electronegativity?
• Sodium or Oxygen?
Oxygen
• Fluorine or Nitrogen?
Fluorine
• Potassium or Iron?
Iron
Greater
ionization energy
Lower
ionization energy
Which has the greater ionization
energy?
• Lithium or Beryllium?
Beryllium
• Zinc or Calcium?
Zinc
• Argon or Sulfur?
Argon
Electronegativity vs. Ionization energy
• The greater the electronegativity, the more
energy is needed to remove an electron.
• The lower the electronegativity, the less
energy is needed to remove an electron.
Atomic Radii
• When atoms have greater electronegativity,
they hold their electrons closer.
• Atoms with a lower electronegativity, have a
greater atomic radius.
Atomic Radii
Reactivity
• The closer atoms are to the noble gases, the
more they want to react so they can become
like them.
Ionic Radii
Compounds
• Sometimes two (or more) different elements
encounter each other and the conditions are
right to form a bond (or bonds) between
them.
• This usually occurs because their electrons are
more stable when they reorganize to form a
bond.
• Often their electrons are organized more like
a noble gases’ electrons after forming a
compound.
• The group of two (or more) different elements
are now called a compound.
Compounds
• bonds form between two different elements.
• Their electrons become more stable (often
arranged more like a noble gases’ electrons).
• They are now called a compound.
Metals
Nonmetals
Three General Bonding Types
• Metal with Nonmetal
• Metal with Metal
• Nonmetal with Nonmetal
Semi-metals
or metalloids
Nonmetals
Metals
Metal with Nonmetal Bonding
• Ionic compounds – the metal gives all of its
valence electrons to the nonmetal.
• Known as – Salts, ions
Metal with Metal
Bonding
• Metallic compounds – the both metals freely
share their valence electrons with each other.
• Known as – alloys
Nonmetal with Nonmetal Bonding
• Covalent compounds – both nonmetals try to
keep hold of their valence electrons as well as
each other’s valence electrons. It ends up being a
constant tug of war (although technically
sharing).
• Known as – molecules
Three General Bonding Types
• Metal with Nonmetal
- form ionic compounds
• Metal with Metal
- form metallic compounds
• Nonmetal with Nonmetal
- form covalent compounds
Three General Bonding Types
• Metal with Nonmetal
- form ionic compounds (one gives, the other
takes)
• Metal with Metal
- form metallic compounds (both freely share
valence electrons - )
• Nonmetal with Nonmetal
- form covalent compounds (both try to hold
on at the same time)
Semi-metals
or metalloids
Nonmetals
Metals
Which kind of compound will these
elements form?
• Iron and Nickel:
Metallic compound
• Sulfur and Calcium:
Ionic compound
• Carbon and Oxygen:
Covalent compound
M + M  metallic
N + N  covalent
M + N  ionic
Which kind of compound will these
elements form?
• Hydrogen and Nitrogen: M + M  metallic
Covalent compound N + N  covalent
M + N  ionic
• Magnesium and Oxygen:
Ionic compound
• Gold and Zinc:
Metallic compound
Semi-metals
or metalloids
Nonmetals
Metals
M + M  metallic
N + N  covalent
M + N  ionic
H
He
Li Be B
C
N
O
F
Na Mg Al
Si
P
S
Cl Ar
K
Ca
Ne
Br Kr
I
Xe
4 e– in valence shell