Microsoft Word - Chemsheets GCSE 1002 (Structure of atoms 2).docx
© www.CHEMSHEETS.co.uk 01-January-2016 Chemsheets GCSE 1002
Atom Atomic number Mass number Number of protons Number of neutrons Number of electrons
C!!"
Cl!"!"
F 9 19
Kr 84 36
B 5 5
Al XXXXXXXXXX
Au!"!"#
Br XXXXXXXXXX
N!!"
P!"!"
Li 3 7
Ne XXXXXXXXXX
Ca 40 20
Be 5 4
Cl XXXXXXXXXX
W XXXXXXXXXX
U XXXXXXXXXX
Mo 42 96
Fe XXXXXXXXXX
Ni XXXXXXXXXX
I XXXXXXXXXX
STRUCTURE OF ATOMS 2
S.L.O.P Shed Loads of Practice!
S.L.O.P Shed Loads of Practice!
AQA Chemistry Unit 1
Atomic Structure & The Periodic Table
Element
Made from only one type of atom.
Atom
The smallest part of an element.
Symbols
One or two letters, first letter always capital,
second letter always lower case e.g.
Na Mg N Cl Fe XXXXXXXXXXAl
Atomic Structure
+
+
+
+
+
++
-
-
-
-
-
- -
Nucleus
Electron
Shell
Proton Neutron
14
N
7
Mass numbe
= Protons + Neutrons in the nucleus
Atomic numbe
= Protons = Electrons
Atoms have no overall charge as the numbe
of positive protons is equal to the number of
negative electrons, their opposite charges cancel.
Subatomic
particle
Location Relative mass
Relative
charge
Proton Nucleus 1 +1
Neutron Nucleus 1 0
Electron Shells 1/2000th -1
The radius of the whole atom is about 0.1nm which is
1 x 10-10 m
The radius of the nucleus is 1/10,000th that of the
whole atom (1 x 10-14 m) , however it contains almost
all of the atom’s mass. This means the atom is mostly
empty space, except for its tiny nucleus.
Electronic Structure
• The negative electrons (x) occupy shells
(energy levels) o
iting the nucleus of the atom.
• The shells are filled from the lowest energy level
(innermost/first shell) outwards.
• The first (innermost) shell is full when it contains 2 electrons.
• All other shells are full when they contain 8 electrons.
Na
x
x
x x
x x
x
x
x
x
x
23
Na
11
• Sodium (Na) has 11 electrons.
• The first shell takes 2.
• The next shell takes 8.
• This leaves 1 for the outer shell.
• Sodium is in group 1 of the periodic table, because it has
1 electron in its outermost shell.
2,8,1
How to work out the number of protons, neutrons
and electrons in an atom:
Isotopes – Versions of an element with a different
number of neutrons.
12
C
6
vs.
Protons = 6
Neutrons = 7
Electrons = 6
Protons = 6
Neutrons = 6
Electrons = 6
• Both are ca
on as they both have 6 protons.
• Therefore they have the same number of electrons (6).
• They are isotopes of ca
on as they contain a different
number of neutrons 6 vs. 7.
• This means they also have different atomic masses.
You must state the numbers of each particle to gain the marks!
13
C
6
7
Li
3
• Protons = atomic number = 3
• Electrons = protons = 3
• Neutrons =
atomic mass – atomic numbe
7 - 3 = 4
-
Questions: Atomic Structure, Isotopes & Electronic Structure
1. Define the keyword atom.
2. Define the keyword element.
3. Draw a labelled diagram of a lithium atom, showing the
protons, neutrons and electrons.
4. Explain what the mass number and atomic number tell us.
5. What is the mass of a proton?
6. What is the charge of a proton?
7. What is the mass of a neutron?
8. What is the charge of a neutron?
9. What is the mass of an electron?
10. What is the charge of an electron?
11. What fraction of the atomic radius, is the radius of the nucleus
of an atom?
12. Give the number of protons (P+), neutrons (N) and electrons (e-
) for the following atoms:
a) Na b) S c) Br d) Ca e) K f) F g) He
h) O i) H j) Fe k) Zn l) Pb m) Li n) Al
13. Define the keyword isotope
14. Compare the similarities and differences between these two
isotopes of oxygen (READ THE GUIDE!). 8
18O vs 8
16O
15. Compare the similarities and differences between these two
isotopes of chlorine (READ THE GUIDE!). 17
37Cl vs 17
35Cl
16. What is the maximum number of electrons that can fill the
first shell?
17. What is the maximum number of electrons that can fill the
second shell?
18. Draw electronic structures for the following elements:
a) H b) He c) Li d) C e) O f) S g) Ca
h) Na i) Al j) S k) Ne
19. What group of the periodic table is oxygen in and why?
20. What group of the periodic table is magnesium in and why?
21. What group of the periodic table is chlorine in and why?
22. Why are the noble gases all in group 0?
+
Compound
Two or more different elements bonded
together.
Reaction equations
When different elements and/or compounds
eact with each other we write word and
symbol equations.
Word equation:
Sodium + Chlorine Sodium Chloride
Symbol equation:
2 Na(s) + Cl2 (g) 2 NaCl (g)
State symbols:
Written in symbol equations to tell you the
state of matter for each substance.
(s) – Solid (l) – Liquid
(g) – Gas (aq) – aqueous
Balancing equations:
The number of atoms of each element
either side of the equation must be the
same.
1. Count the number of atoms of each element on both sides.
Al = 1
O = 2
Al = 2
O = 3
2. Find common denominators between the numbers
and multiply so they match.
__ Al XXXXXXXXXX__ O2 __ Al2O3
Al = 1
O = 2
Al = 4
O = 3
__ Al XXXXXXXXXX__ O2 __ Al2O3
= 4
x 2 = 6
x 4 = 4
x 3 = 6
3. Put the numbers you multiplied by in the equation’s gaps.
Al = 1
O = 2
Al = 2 x 2
O = 3
__ Al XXXXXXXXXX__ O2 __ Al2O3
= 4
x 2 = 6
x 4 = 4
x 3 = 6
4 3 2
Chemical Formulae
Tell us how many atoms of each element a molecule or
compound contains.
Cl2 = 2 atoms of Cl
onded as molecule
2 Cl2 = 2 molecules
of Cl2
Cl Cl
Cl Cl
Cl Cl
Conservation of mass
Mass is conserved, so it will be equal on
oth sides of a chemical equation.
4 Al XXXXXXXXXXO2 2 Al2O3
So five grams of aluminium and 3 grams of
oxygen will give 8 grams of aluminium
oxide!
O
O Ca CAl Al
O
O
O
O
Al2O3 CaCO3
El
em
en
t
C
o
m
p
o
u
n
d
Development of the atomic model.
New evidence has led to the atomic model changing over
time.
The Plum Pudding model of the atom:
The Rutherford alpha particle experiment:
Niels Bohr:
Niels Bohr suggested that the electrons occupied energy
levels (shells su
ounding the atom).
James Chadwick:
James Chadwick discovered that the nucleus also contains
neutrons.
-
-
-
-
-
-
-
-
-
When the electron was discovered,
J.J Thomson suggested the atom
was a positively charged sphere
with
negatively charged electrons
embedded in it.
Protons and neutrons were not
included in the plum pudding as
they had yet to be discovered.
Ernest Rutherford tested the plum
pudding model by firing positively
charged alpha particles at gold
atoms.
Most of the alpha particles passed
straight through, which suggested
the atom was mostly empty space.
A tiny proportion positive alpha
particles scattered off in different
directions, this suggests they
collided with, and were repelled
y, a tiny nucleus of positive
charge.
This new evidence proved that the
plum pudding model was wrong.
+
α2+α2+α2+α2+α2+
α2+
α2+α2+α2+α2+
El
em
en
t
C
o
m
p
o
u
n
d
H Cl
H Cl
2 HCl + 2 H2O
M
ix
tu
e
o
f
C
o
m
p
o
u
n
d
s
O
H H
O
H H
Mixture
Two or more elements or compounds not
chemically combined. The chemical properties
of each substance in a mixture remain unchanged.
Physical processes
Physical processes can be used to
separate mixtures. They do not result in a
chemical reaction.
Filtration
Filtration is used to separate a mixture of a liquid
and solid for example, sand and water.
Crystallisation
Crystallisation is used to obtain a solid form of a
dissolved substance, for example getting solid salt
from salty water.
Distillation
Distillation is used to separate mixtures of liquids with different boiling points.
For example, ethanol and water.
Chromatography
Chromatography is used to separate mixtures
containing colours, such as pen inks or food
colourings.
Filter funnel
Filter pape
Solid collects in filter pape
Conical flask
Liquid collects in conical flask
Water evaporates
Solution heated with Bunsen Burne
Solution of
dissolved
substance
Evaporating Basin
Gauze
Tripod
Solid crystals remain
Round bottomed flask
Collection flask
Water in
Water out
HEAT
Mixture of liquids with
different boiling points
Evaporation
Vapours rise up sill head into water
condense
Thermomete
1. The mixture of liquids is
heated.
2. The substance with the
lowest boiling point
evaporates first.
3. Its vapours rise up the
sill head and are cooled
in the water condenser.
4. The vapours condense
into a liquid and collect
in the