Download Year 9 Science Revision Unit: Elements NGA PUMOTU O

Year 9 Science Revision
Unit: Elements
NGA PUMOTU O PAPATUANUKU/ ELEMENTS OF THE EARTH’S CRUST
Key words:
element
atomic number
molecule
mixture
neutron
nucleus
compound
proton
atom
electron
Key definitions to learn:
element
compound
molecule
mixture
physical property
atom
electron
proton
neutron
a pure substance composed of only one type of atom
a pure substance composed of more than one type of atom
two or more atoms chemically combined in a fixed ratio
two or more elements or compounds that are easily separated
can be seen or tested without changing the substance
the smallest particle of matter to exist on its own
a negative sub-atomic particle that orbits the nucleus
a positive sub-atomic particle that is found in the nucleus
a neutral sub-atomic particle that is found in the nucleus
Key Learning Points:
All Matter is made up of atoms. Each element differs from another by having a unique
number of protons and electrons.
Elements and their symbols.
The symbols and names of the first 20 elements plus the common metals Fe, Cu, Zn,
Ag, Sn, W, Pt, Au, Hg, Pb need to be MEMORISED. Here is a Periodic Table from which
to get them .
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Year 9 Science Revision
Unit: Elements
The Periodic Table
1. Each column in a periodic table is called a group. Elements in a group
have similar chemical reactions.
2. Each row in a periodic table is called a period. As you move across a
period, the number of electrons increases until the electron shell is full
at the end of the period.
Distinguishing between metals and non-metals
3. Metals are found on the left hand side of the Periodic Table, while non-metals are
found on the right hand side of the Periodic Table. A line which steps down the
periodic table divides the metals from the non-metals. The line starts between Beryllium
and Boron.
4. Physical properties are used to distinguish between elements that are metals and
elements that are non-metals. These properties are summarised in the table.
Physical Properties
Metals
Non-metals
solid at room temperature, except Hg
can be either solid or gas but only Br is a liquid
shiny when scratched
dull when scratched
bendy (malleable)
are brittle, not bendy
can be pulled into wires (ductile)
are not ductile
good conductors of heat
poor conductors of heat
good conductors of electricity
poor conductors of electricity
grey in colour except for Au and Cu
colourful
Formulae of elements and compounds
Elements
Hydrogen gas
Oxygen gas
Magnesium metal
Zinc metal
Nitrogen
Sulfur
H2
O2
Mg
Zn
N2
S8
Compounds
Water
Carbon dioxide
Hydrochloric acid
Copper sulphate
Sodium Chloride
Magnesium oxide
H2O
CO2
HCl
CuSO4
NaCl
MgO
Number of atoms in molecules of elements and compounds
Molecule
MgCl2
CaCO3
Al(OH)3
Number of each atom
One Mg and two Cl atoms
One Ca, one C, and 3 O atoms
One Al, 3 O, and 3H atoms
Total atoms
3
5
7
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Year 9 Science Revision
Unit: Elements
Atomic structure
Here is a diagram showing the structure of an Carbon atom
Atomic notation
Particles in an
atom
Proton
Neutron
Electron
charge
positive
neutral
negative
Where in the atom is it
found?
nucleus
nucleus
orbiting in energy levels
What does the number of protons tell us?
 Atoms of different elements have a specific number of protons in their nucleus.
 The number of protons inside an atom is called the atomic number
 The atomic number is the smaller number next to the element on the Periodic Table.
e.g All atoms of Na have a proton number of 11 i.e. they have 11 protons
11Na
How can we tell how many neutrons there are in a nucleus?
The number of protons + the number of neutrons is called the mass number.
To find the number of neutrons in an atom of an element:
No. of neutrons = mass no. – no. of protons
23
Na
The mass number is the larger number next to the element on the Periodic Table
How can we tell how many electrons there are in an atom?
The number of electrons is always equal to the number of protons so the atom is neutral.
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Year 9 Science Revision
Unit: Elements
No. of protons = no. of electrons
Using atomic notation to determine its parts
Elements
Atomic
Number of
Number
Protons
Hydrogen
1
1
Carbon
6
6
Neon
10
10
Aluminium
13
13
Potassium
19
19
Gold
79
79
Mass
Number
1
12
20
27
39
197
Number of
neutrons
1–1=0
12 – 6 = 6
20–10 = 10
27–13 = 14
39 -19 = 20
197-79 = 88
ELEMENT
-
is made up of only one type of atoms
cannot be broken down into a simpler type of matter
can exist as either atoms (e.g. Ar argon) or molecules (e.g N2 nitrogen).
COMPOUND
-
Is made up of two or more types of atoms bonded together.
Can be broken down into a simpler type of matter (elements) by chemical means
(but not by physical means),
Has properties that are different from its component elements.
NaCl(table salt), Na is a reactive silver metal, Cl2 a poisonous green gas
always contains the same ratio of its component atoms.
MIXTURE
consists of two or more different elements and/or compounds physically
intermingled,
- can be separated into its components by physical means, and
- often retains many of the properties of its components. Salty water tastes
of salt.
-
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Year 9 Science Revision
1. Complete the table and give the
Symbol
Name
H
F
N
S
O
Unit: Elements
Revision Questions:
name for each element symbol:
Symbol
Name
Li
Cl
Ne
He
Al
2.Give the Symbol for each of these elements
Name
Symbol
Boron
Beryllium
Argon
Magnesium
Phosphorus
Name
Calcium
Potassium
Carbon
Silicon
Sodium
Symbol
3. Make 7 sentences by combining a word from each of the first 2 columns with a
phrase from the 3rd column. For example : Atoms are small particles
be broken down into anything simpler.
Atoms
Molecules
are
two (or more) elements or compounds mixed,
but not joined, together.
small particles.
Elements
can
made when atoms join together.
Compounds
Mixtures
cannot
made from the chemical combination of 2 or
more elements.
made from only one type of atom.
be separated into pure substances.
1. ______________________________________________________________________________
2. ______________________________________________________________________________
3. ______________________________________________________________________________
4. ______________________________________________________________________________
5. ______________________________________________________________________________
6. ______________________________________________________________________________
7. ______________________________________________________________________________
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Year 9 Science Revision
Unit: Elements
4. Label the following diagrams as Element, Compound or Mixtures
5. Draw a diagram for each of the 2 atoms
Nitrogen
14
Sodium
23
N
7
Na
11
6. Use the Periodic Table and your knowledge to complete the table
Element
Symbol
Atomic Number of Number of
Mass
Number
Protons
electrons
number
Calcium
20
40
9
19
13
Potassium
19
39
Copper
29
7. Sort these elements into metal or non-metal:
Na
Ne
K
Cl
Li
F
N
Ca
C
Metals
Non-metals
Number of
neutrons
14
35
Br
8. Calculate the number of atoms in each of the molecules
Molecule
Number of each atom
NaCl
NH4OH
Al2(CO3)3
Total atoms
9. a. Decide whether the following two elements are metal or non-metal
Magnesium: ____________________
Oxygen:______________________
b. Give 3 physical properties of Magnesium or Oxygen that helps you to decide
1. ________________________________ 2.________________________________
3_______________________________________________________
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Year 9 Science Revision
Unit: Elements
Draw a mind map for this unit:
Add to it, as you develop your learning.
Elements
Well done you have completed another revision unit.
Now reflect on how you can improve further:
Which aspects of the unit do I need to revise more carefully?
Which aspects of the unit do I need help with?
How will I seek this help?
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