1. Section 4 – pg 148 Nonmetals, Inert Gases, and Semimetals
Chapter 4
Section 4 – pg 148
Nonmetals, Inert Gases, and Semimetals

2. Properties of Nonmetals
Pg 149
Properties of Nonmetals
An element that lacks most of the properties of a metal
Most nonmetals are poor conductors or electric current and heat. Solid nonmetals are dull and brittle
Phosphorus
Charcoal
Sulfur

3. Pg 149
Physical Properties
Gas at room temp: Nitrogen, Oxygen, Fluorine, Hydrogen, Chlorine
Liquid at room temp: Bromine
Solid at room temp: Carbon, Iodine, Sulfur, Phosphorus, Selenium
Properties tend to be opposite of metals: dull, brittle, not malleable or ductile

4. Pg 150
Chemical Properties
Nonmetals usually gain or share electrons when they react with other atoms
When metals react with nonmetals, the electrons move from the metal to the nonmetal

5. Families with Nonmetals
Pg 150
The Carbon Family
Each element in the carbon family (Group 14) has atoms that can gain, lose, or share four electrons when reacting with other elements

6. The Nitrogen Family Pg 151 The Nitrogen Family (Group 15)
Contains 2 nonmetals that usually gain or share three electrons when reacting with other elements
Diatomic Molecule: a molecule that consists of two atoms
All living things need nitrogen but few can use it in its molecule form
Some bacteria can use nitrogen to form compounds (fixation), these compounds are often found in soil
Plants get the nitrogen from the soil, other animals get it from eating the plants or eating the animals that ate the plants

7. Pg 152
The Oxygen Family
Oxygen Family (Group 16) contains three nonmetals: oxygen, sulfur, selenium
Usually gain or share electrons when reacting with other elements
Oxygen is normally a diatomic molecule – form we breathe
Oxygen sometimes forms a triatomic (three-atom) molecule: called ozone
Collects in a layer in the upper atmosphere where it screens out harmful radiation from the sun (but is a dangerous pollutant at ground level because it is highly reactive)

8. The Halogen Family The Halogen Family (Group 17) Pg 153
Known as halogens – “salt forming”
Typically gains or shares one electron when it reacts with other elements
All are very reactive and the uncombined elements are dangerous to humans
Chlorine is used in very small amounts to kill bacteria in water
Fluorine is used in toothpaste
Bromine will burn skin on contact

9. Pg 154
Inert Gases – Group 18
Usually do not form compounds b/c atoms of inert gases do not usually gain, lose, or share electrons
The inert gases tend to be unreactive
AKA – noble gases
Exist in earth’s atmosphere in small amounts

10. Pg 154
Hydrogen
The chemical properties differ so much from others, it cannot be grouped in any family
Atoms have one electron, and one proton
Sometimes also has one neutron
Makes up 90% of the atoms in the universe but rarely found on Earth as pure substance
Usually combined with oxygen in water

11. Pg 155
Semimetals
Have properties of metals but also have properties of nonmetals
All are solid at room temp
Are brittle, hard and somewhat reactive
The most useful property of the semimetals is their varying ability to conduct electric current
Semiconductors: substances that can conduct electric current under some conditions but not under others
Used to make computer chips, transistors, and lasers

12. Chapter 4 Section 4 Homework – pg 155

13. 1A. What are some properties of nonmetals?

14. 1B. What happens to the atoms of most nonmetals when they react with other elements?

15. 1C. How do the physical and chemical properties of the halogens compare with those of the inert gases?

16. 2A. Where in the periodic table are the semimetals found?

17. 2B. What are three uses of semimetals?

18. 2C. What property makes semimetals useful as “switches” to turn a small electric current on and off?