Section 2.1
Introduction to elements
Why are elements studied in chemistry?
1) Chemistry is the study of matter and its properties.
2) An element is a pure substance that cannot be broken
down or separated into simpler substances. Each element
is one kind of atom.
3) By studying elements, we can learn more about the
structure of matter.
2.1 Elements
Element names and symbols
1) Because elements have different names in different languages,
chemists use international symbols for them
2) Chemical symbols consist of one or two letters.
3) Ancient names are used as the source of many of the symbols.
Example: Hydrogen (H)
Hydros genes = water forming
See page 44
All elements are represented by symbols.
Here are just a few element symbol examples:
Common Elements
See page 45
Hydrogen (H)
1)
2)
3)
4)
5)
Colorless, odorless, tasteless, and highly flammable gas.
Makes up over 90% of the atoms in the universe
Used in producing fertilizers
Lighter than air
Automobiles made to be run on hydrogen rather than
gasoline.
Why?
No pollution like producing CO2, the only by-product is H20 ! Yay
water!!
Oxygen (O) - gaseous element we breathe
See page 45
21 % of the atmosphere
Reacts with most other elements
Major component of water which covers ¾ of our planet
Our cells use oxygen to convert sugar into energy we can use
Plants produce Oxygen as a by-product of photosynthesis.
For your info, about 65% of your body’s mass is made of Oxygen!!!
Iron (Fe)
See page 45
- mixed with carbon to make steel
- very strong metal
- good structural material, but can rust when mixed with
water and oxygen
Iron in a river turns water and rocks red
Sodium (Na)
1) Very soft metal that can even be cut with a knife !!!
2) It also reacts so fast and so violently with water
3) Cannot be used to even hold waterwould react and could cause an explosion
(c) McGraw Hill Ryerson 2007
Chlorine Cl
1) Chlorine (Cl) - yellow-green gas that is highly toxic
2) Safe enough in pools (used to kill bacteria) but in high
concentrations it can be deadly
3) It combines with sodium to form table salt !
Cl
See pages 46 - 47
Other Common Elements
1) Mercury (Hg) - liquid at room temperature metal.
2) Silver (Ag) - precious metal mined in British Columbia
3) Silicon (Si) - brittle, grey, semiconductor that is second most
common element in Earth’s crust.
Hg
Ag
Si
Homework
Worksheet 2.1
(c) McGraw Hill Ryerson 2007
(c) McGraw Hill Ryerson 2007