1. Metals, Non-metals and Metalloids
Chapter 20
Metals, Non-metals and Metalloids

2. Section 2--Nonmetals
Most of your body’s mass is made of oxygen, carbon, hydrogen and nitrogen
Calcium makes up the remaining 4% of body mass
Nonmetals—are elements that usually are gases or brittle solids at room temp.
Usually gases or brittle solids at room temp
They are not malleable or ductile
They are not good conductors

3. All nonmetals except hydrogen are found at the right of the stair-step line.
Noble gases—group 18—make up the only group of elements that are all nonmetals.
Most nonmetals can form ionic and covalent compounds
Hydrogen—90% of Earth’s atoms
Most hydrogen on Earth is part of water
When water breaks down into elements, hydrogen becomes diatomic

4. Halogens Halogens—Group 17—are very reactive
Form compounds that have many uses—toothpaste, disinfectants, etc.
If a halogen gains an electron from a metal, an ionic compound called salt is formed
In the gaseous state, halogens form reactive diatomic covalent molecules
Halogens are ID’d by their distinctive colors

5. Uses of Halogens—check pg. 619
Noble gases—noble gases exist as isolated atoms
They are stable because their outermost energy levels are full
No naturally occurring noble gas compounds are known
The stability of noble gases makes them useful
Ex: balloons, neon lights, electric lightbulbs, etc.

6. Section 3 Notes—Mixed Groups