Download S3 Numeracy Booklets – Atomic Structure

Lesmahagow High School
National 4/5 Chemistry
Topic 2 Problem Solving
Numeracy Booklets – Atomic Structure
Structure of the atom:
http://www.calstatela.edu/faculty/acolvil/mineral/atom_structure1.jpg
Sub atomic particle
Position
Charge
Mass
proton
nucleus
+
1 amu
neutron
nucleus
0
1 amu
electron
shells
-
0
atomic number = number of protons
number of electrons = number of protons
atomic mass = number of protons + number of neutrons
Isotopes:
Isotopes are atoms of the same element with the same atomic number but
different atomic mass i.e. same number of protons different number of neutrons.
relative atomic mass = total mass of 100 atoms
100
Worked Examples:
1.
How many protons does a carbon atom have?
Ans: Carbon has atomic number 6 so 6 protons.
2.
How many electrons does a sodium atom have?
Ans: Sodium has atomic number 1 1 , so 1 1 protons and therefore 1 1 electrons.
3.
How many neutrons does a magnesium atom have?
Ans: Magnesium has atomic number 1 2, so 1 2 protons, and a mass number of 24.
number of neutrons
4.
= atomic mass – atomic number
= 24 – 1 2
= 1 2 neutrons
What is the difference between an atom of chlorine-35 and an atom of
chlorine-37?
Ans: Chlorine atoms have an atomic number of 1 7, so 1 7 protons.
Chlorine- 35 atoms have a mass of 35.
So number of neutrons = mass number – atomic number
= 35 - 1 7
= 1 8 neutrons
Chlorine- 37 atoms have a mass of 37
So number of neutrons = mass number – atomic number
= 37 - 1 7
= 20 neutrons
So difference between the two isotopes is 2 neutrons.
5.
What is the relative atomic mass of chlorine?
35
Ans: Chlorine has 2 isotopes
RAM = Total mass of
35
37
Cl atoms + Total mass of
1 00
= (75 x 35) + (25 x 37)
1 00
= 35. 5
Cl = 75% of all chlorine atoms
Cl = 25% of all chlorine atoms
37
Cl atoms
Questions
1.
What is the atomic number of helium?
2.
How many protons are in the nucleus of a Uranium atom?
3.
Which element has 32 electrons?
4.
How many neutrons does a lithium atom have?
5.
What is the difference between
6.
What is the same for atoms of
7.
What is the relative atomic mass of lithium given the following information?
8.
6
Li = 10% of all lithium atoms
7
Li = 90% of all lithium atoms
63
23
What is the % of each isotope
boron is 10.5?
Cu atoms and
65
Cu atoms?
Na and atoms of
10
B and
11
24
Mg?
B if the relative atomic mass of
Chemical code breaker:
Can you create a series of 6 unique questions relating
to atomic structure, the answers to which will give
the secret combination to the Chemistry department’s
safe?
The six numbers are
35
22
11
6
99
22
The questions must involve at least one mathematical process and two numbers
related to the atomic structure of elements.
i.e. if you wanted to get the number 24 you could ask:
What number is equal to the atomic mass of carbon + the atomic number of
magnesium? Ans: atomic mass of carbon is 12; atomic number of magnesium is 12,
so 12 + 12 = 24.
Extra marks will be awarded for ingenuity and complexity.
1.
2.
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6.