Combining Elements

Chapter 2

Compounds

When two or more elements combine we get a compound. Examples are water and air.

Salt or NaCl is also a compound

Types of Bonds

When atoms combine they can attach themselves in one of three ways

1) Covalent Bond2) Ionic Bond3) Metallic Bond

Covalent Bond This occurs when

an atoms outer electrons are shared with another atom

Water is a more common example of this type of bond

Ionic Bond Atoms for this

bond when they are electrically charged. A positive charged atom will bond with a negative charged atom such as a magnet

Metallic Bonds

When metals bond they usually form metallic bonds.

Electrons move freely between atoms and this is why metals conduct electricity so well

Mixtures Heterogeneous • Occurs when two or more

substances are mixed together, but each substance still looks the same. Sand and water is an example

Homogeneous• The substances are

mixed together and you can’t see the individual substances. Mix sugar and water and the sugar dissolves. You’ve created a solution or a homogeneous mixture

Homogeneous vs. Heterogeneous

Today 9/25/07

Complete Atomic numbers, mass, and names review sheet

We will play a DVD review game

Class Work Assignment

Page 56 (Chapter 2 Review) Complete numbers 2, 6, 11, 12,

13, 14, 16, 17, 25, and 27

Tomorrow

We will have a test over chapters 1 & 2.

Look over the book, notes, and work handed back

Text Book Assignment

General Science Page 56 11-21, 25 Page 58 1-12

Pre-Chem Page 31 Vocab. 1-10, R.Q. 2,4,5,7,14,

Ex. 11,13,14, Prob. 3,4