Chemistry 1 Revision: C1 Fundamental Ideas
Atoms and the Periodic Table
Chemical reactions and bonding
atoms attract bond compounds electrons elements full
gain ions lose metals molecules negative
non-metals
one positive shared seven shell strong transferred
atoms centre
electrons element
first
full group H2
H2O left Na
neutrons noble gases
nucleus periodic table
properties
protons
right second shell sodium stable
unreactive water +1
–1 0
All substances are made of a............... A substance that is made of only
When e.......................... react, their atoms join with other atoms to form
one sort of atom is called an e.............................
c.......................... This involves losing, gaining or sharing e......................... to form
x
x
i............... or m.......................... so that a.............. can gain a f........... outer shell of
e.........................
n......................... containing p.........................
x
and n..........................
Complete the table:
proton
neutron
electron
charge
mass
electrons
Ionic bonds:

Formed from m................. and n....................................

metals l............... electrons to form p.................... ions
 non-metals g............... electrons to form n....................... ions
Complete the labels on the diagrams to show formation of sodium chloride
(only outer shell electrons are shown):
Atoms of each element are represented by a chemical symbol, e.g.
x
Atomic number = number of p.........................
11
x
x
= number of e.........................
Na
Symbol
23
Na = s........................
x
Atoms of the same e................. have the same number of p....................
x
x
E.............................. are arranged around the n.......................... in shells.
 The f................. shell holds a maximum of 2 electrons
 The s......................... and subsequent shells hold a maximum of 8
electrons
+
Complete the diagrams showing electron arrangement. The first one has
been done for you.
3
Li
7
8
O
16
10
Ne
20
sodium has o.......... e...................... in its outer
xx
x
x
s.............. chlorine has s.................
e...................... in its outer s..............
To gain a f.......... outer s.............. sodium
Atomic mass = number of p................... + n....................
17
Cl
35.5
x
x
x
x
xx
xx
xx
l............ one electron and potassium
x
x
x
x
g................ one e...................... : the electron is
t.......................
–
Sodium has formed a p........................ charged
ion and chlorine has formed a n.........................
charged ion. The opposite charges a................
to form a very s................... ionic b.............
Covalent bonds

Formed from n...............................

E....................... are s...................

Atoms held together by s............... b.......... to form m.........................
Complete the labels on the diagrams to show formation of chlorine (only
outer shell electrons are shown):
2, 1
.......................
x
x
......................
.............................
Elements are shown in the P...................... T................... Metals are found
on the l................. and c..................., non-metals are found on the r................
of the P...................... T.................... Elements in the same g.................... have
similar p......................... because they have the same number of
e............................. in their outer s.................., e.g. all group 1 elements
react with w.....................
sodium
+
............... +
water

sodium hydroxide
+
hydrogen
NaOH
+
..................
............. 
Elements in g................... 0 of the periodic table are called the n...............
xx
x



xx
xx 

x x
x

xx

Each chlorine a............... has s..................
e......................... in their outer s................
Each atom shares one e................... with the
other atom so both have a f.......... outer
s..............
Balancing equations and reacting masses
Chemical reactions can be represented by word equations or by balanced
symbol equations – there must be the same number and type of atoms on each
side of the arrow.
Chemical formulae cannot be changed – you can only get more atoms by
putting large numbers in front of chemical formulae e.g.
Hydrogen + oxygen  water
H2
+
O2
 H2O
2
Number of oxygen atoms:
g................. They are u........................... because their atoms have a f..........
Balance for oxygen atoms:
H2
outer shell of e....................... which makes it s.................
Number of hydrogen atoms:
2
2 H2
Shows the number and type of atoms in an element or compound e.g.
1 atom of carbon
Formula mass
=
CO2
1 x carbon =
2 x oxygen =
2 atoms of oxygen
1 x 12 = 12
2 x 16 = 32
12 + 32 = 44 g
Use atomic mass from periodic table
Complete the following using the periodic table to help:
H2O: ........... atoms of h.......................... .......... atoms of o.......................
Formula mass = ..........................................................................................................
1
 2 H2O
O2
2x2= 4
+
O2
 2 H2O
Atoms in Reactants:
Atoms in Products:
H: 2 x 2 = 4
H: 2 x 2 = 4
O:
=2
O: 2 x 1 = 2
No atoms are lost or made during a chemical reaction so the mass of the
products equals the mass of the reactants e.g.
Balance for hydrogen atoms:
Chemical formula
+
CaCO

CaO
+
CO
3
2
Formula mass
1 x Ca = 1 x 40 = 40
Formula mass =
1 x C = 1 x 12 = 12
1 x Ca = 1 x 40 = 40
3 x O = 3 x 16 = 48
1 x O = 1 x 16 = 16
100
56
Total formula mass of reactants =
Total formula
100
Formula mass =
1 x C = 1 x 12 = 12
2 x O = 2 x 16 = 32
44
mass of products =
56 + 44 = 100