2. Chemical Bonding
Bonding – attractions between atoms or ions
There are several types of chemical bonds,
but we will discuss three of the strongest
types
1. Covalent bonds
2. Metallic bonds
3. Ionic bonds
3. Covalent Bonds
Covalent bonds – bonds formed from atoms
sharing pairs of electrons
Molecules formed this way: sugar, water
- NO charged particles / ions involved
- Sharing electrons between atoms
Each atom “donates” one electron to the
shared pair
4. Covalent Bonds
- Two atoms can share up to 3 pairs of
electrons
1 shared pair = single covalent bond
2 shared pairs = double covalent bond
3 shared pairs = triple covalent bond
5. Covalent Bonds
- Each shared pair represented as a line in a
structural formula
Example: H - H
*this is a single covalent bond
**Goal of bonding is to fill the outer energy level
and become stable
6. Covalent Bonds – Electron dot
diagrams
Valence electrons – electrons in the
outermost energy levels of an atom
Electron dot diagrams show the valence
electrons as dots surrounding the
chemical symbol
The chemical symbol represents the
nucleus and all inner level electrons
Electron dot diagrams show only the electrons in the
outer energy level of an atom.
7. Covalent Bonds – Electron dot
diagrams
Each
hydrogen
shares one
pair of
electrons with
the oxygen
atom
8. Metallic bonds
2. Metallic bond – Closely packed metal atoms
- Outer energy levels of metal atoms overlap
- Valence electrons can move and flow freely
throughout the substance
- Allows flexibility of material to bend
- Allows easy flow of electricity through material
9. Ionic Bonds
3. Ionic bond – bond between oppositely
charged ions, involving a total transfer of
electrons between atoms
- Ion – a charged particle
- Cations (which lose electrons and become
positively charged) bond to Anions (which
gain electrons and become negatively
charged)
10. Ionic Bonds
- One atom gains an electron(s) and one atom
loses an electron(s)
- The now oppositely charged ions are attracted
to each other due to magnetism
Opposite charges attract
11. Ionic Bonds
• Ionic bonds usually are formed by bonding
between metals and nonmetals.
13. Ionic Bonds
• When atoms form an ionic compound, their
electrons are shifted to the other atoms, but
the overall number of protons and electrons
of the combined atoms remains equal and
unchanged. Therefore, the compound is
neutral.
14. Ionic Bonds
- Ionic compounds are networks but there is a
basic ratio of cations to anions
Formula unit – the basic ratio of ions
Example: NaCl 1 Na : 1 Cl
