1. Chapter 5: Atoms & Bonding
Stuff we still need to cover!

2. Ionic Bonds (5-2)
Polyatomic ions - ions that are made of more than one atom. “poly” means many. The group of atoms act as a unit. Ex. Bicarbonate HCO3- (a component of baking soda)
Subscript - Tells you the ratio of elements that comprise the compound. In the above polyatomic ion there is 1 H to 1 C to Oxygen atoms.

3. Naming ionic compounds
In ionic compounds, the name of the positive ion comes first, then the negative ion. (metal then non-metal)
If the negative ion is a single element the name changes to “ide” ex. MgO is Magnesium Oxide (not Oxygen)
If the negative ion is polyatomic the name usually ends in -”ate” or -”ite”
Ex. Ca(NO3)2 calcium nitrate

4. Covalent Bonds 5-3
Polar bonds - A covalent bond in which electrons are shared unequally. This causes one side of the molecule to have a positive charge and the other to have a negative charge. Water is an example.
Nonpolar bonds - A covalent bond in which the electrons are shared equally. There is no resulting charge on the molecule. Carbon dioxide is an example.

5. Covalent Bonds
The number of covalent bonds that a non-metal atom can form is equal to the number of electrons it needs to get to 8.
A double bond forms when atoms share two pairs of electrons.
A triple bond forms when atoms share three pairs of electrons. (see overhead)

6. Bonding in Metals 5-4
An alloy is a mixture of 2 or more elements, at least one of which is a metal. Ex. Brass is a mixture of copper and zinc. Fe,C,Ni, and Cr = Stainless Steel
Metal atoms combine in regular patterns with the positive ions packed together and the electrons bobbing and weaving around them. (forming a “sea of electrons”)

7. Metallic Properties
The “sea of electrons” model of metallic bonding explains metallic properties, such as:
Malleability, ductility, luster, high electrical conductivity, and high thermal (heat) conductivity