Download Lauren Gill O`Brien Grade 9 Science 4.1 Organizing the Elements

4.1 Organizing the Elements
Atomic Mass – the average mass of an atom of an element (of all occurring isotopes)
Mendeleev – organized the known 64 elements into a periodic table which made the
study of chemistry more manageable
Mendeleev’s periodic law- if the elements are arranged according to their atomic mass, a
pattern can be seen in which similar properties occur regularly
4.3 Activity
Modern Periodic Law – If the elements are arranged according to their atomic number a
pattern can be seen in which similar properties occur regularly.
Atomic radius – The distance from the nucleus to the outer edge of the atom
4.4 Groups of Elements
Chemical Group – the set of elements in the same column that have similar physical and
chemical properties
Noble Gases
o Group 18
o Full outer orbit
o Unreactive
Alkali Metals
- Group 1
- 1 electron in outer orbit
- Very reactive
- Never found alone in nature always in a compound
Halogens
-
Group 17
7 electrons in outer orbit
Very reactive
Found in nature as compounds
Hydrogen
Lauren Gill O’Brien
Grade 9
Science
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it is colourless, tasteless, odorless
highly flammable
reacts with halogens
Metalloids
- have both metal and non-metal properties
- not in a group together but zig zag between the metals and non-metals
- silicon
o shiny, silvery – like metals
o not malleable, poor conductor – like non-metals
Periods – horizontal rows of elements
- show similarities
Lauren Gill O’Brien
Grade 9
Science
4.6
Metals – alloys
Polymers – Wool, leather, linen, cotton
- glue, rubber
- nylon, plastics
-a material made of long molecules
Ceramics – stone, pottery, flint
-glass
- a material made by heating minerals and rocks
Composites – Straw/clay
-fiberglass
- a material formed by combining two other materials.
4.7
Ozone
Lauren Gill O’Brien
Grade 9
Science