1. ..and so overall charge equals zero
How Many Electrons
The atoms of any element have an equal number of protons and electrons.
Atom
Protons
Neutrons
Electrons
Helium 2
Copper 29 35
Cobalt 27 32
Iodine 53 74
Germanium 41
..and so overall charge equals zero

2. How Many Electrons Fill in the blank columns 5 5 11 19 19 39 24 24 52
Activity
How Many Electrons
Fill in the blank columns
Atom
Protons
Neutrons
Electrons
Atomic number
Mass Number
Boron 5 6
Potassium 19 20
Chromium 24 28
Mercury 80
121
Argon 18 22 5 5 11 19 19 39 24 24 52 80 80
201 18 18 40
Note – atomic number is defined as the number of protons rather than electrons because atoms can lose (or gain) electrons but do not normally lose protons

3. Drag the statements at the top onto the correct
Activity
Drag the statements at the top onto the correct
side of the table
A drag and drop activity

4. Drag the statements at the top onto the correct
Activity
Drag the statements at the top onto the correct
side of the table
A drag and drop activity

5. How Are Electrons Arranged?
Electrons are not evenly spread.
The exist in layers known as shells.
The arrangement of electrons in these shells is often called the electron configuration.
1st Shell
2nd Shell
3rd Shell
4th Shell

6. How Many Electrons per Shell?
Each shell has a maximum number of electrons that it can hold.
The maximum
1st Shell: 2 electrons
2nd Shell: 8 electrons
3rd Shell: 8 electrons

7. Working Out Electron Arrangements
How many electrons do the element atoms have? (This will equal the atomic number).
Draw them into the shells working outwards until you have used them all up.
Drawing neat diagrams helps you keep track!
1st Shell: Fills this first
2nd Shell: Fill this next

8. The Electrons in Carbon
A drag and drop activity

9. The Electrons in Neon
A drag and drop activity

10. The Electrons in Silicon
A drag and drop activity

11. Electrons in Phosphorus
A drag and drop activity

12. The Electrons in Argon
A drag and drop activity

13. The Electrons in Sodium
A drag and drop activity

14. The Electrons in Fluorine
A drag and drop activity

15. The Electrons in Aluminium
A drag and drop activity

16. The Electrons in Nitrogen
A drag and drop activity

17. The Electrons in Sulfur
A drag and drop activity

18. The Electrons in Oxygen
A drag and drop activity

19. The Electrons in Chlorine
A drag and drop activity

20. The Electrons in Magnesium
A drag and drop activity

21. Happiness is…………………. A full outer shell

22. Ions and Electron Structures
Ions are atoms that have either extra electrons added or electrons removed. e.g.
Atoms
Protons
Electrons
Gain 1 electron
Lose 1 electron
1+ ion
Protons
Electrons
So in ions the number of electrons no longer equals the number
of protons
1- ion
Protons
Electrons

23. Positive Ions
These are ions formed by the atom losing one or more electrons.
They are called cations. This is because during electrolysis they move towards the cathode. (Or because they are “pussytive”!).
The charge on the ions is equal to the number of electrons that the atom has lost.
In equations the charge is usually shown above and to the right of the symbol. (E.g. Mg2+ ).
Lost 1 e- +
It is nearly always metal atoms that lose electrons
Ions usually have
OUTER
electron shells that are either completely full or else empty
Lost 2 e- 2+
Lost 3 e- 3+

24. The Electrons in a Sodium Ion
In the sodium atom
Atomic number = number of protons = 11
Number of electrons = 11 23 Na 11
Na+ Na
Bye!
Electron lost
Electron arrangement: (Incomplete Shell)
Electron arrangement: 2.8 (Full Shells)

25. The Electrons in a Magnesium Ion
In the magnesium atom
Atomic number = number of protons = 12
Number of electrons = 12 24 Mg 12
Mg2+ Mg
Bye!
2 electrons lost
Electron arrangement = (Incomplete shell)
Electron arrangement 2.8 (Full Shells)

26. The Lithium Ion 3 How many electrons?
Activity
The Lithium Ion 3
How many electrons?
How many electrons in the first shell?
How many electrons in the second shell?
What electron arrangement?
How many electrons to lose?
New electron arrangement? Include a diagram 7 Li 3 2 1
2.1
1st Shell = 2: full
2nd Shell = 1: not full Li
Li+ 1
Bye!
2.(0)

27. The Boron Ion 5 How many electrons?
Activity
The Boron Ion 5
How many electrons?
How many electrons in the first shell?
How many electrons in the second shell?
What electron arrangement?
How many electrons to lose?
New electron arrangement? 11 B 5 2 3
2.3
1st Shell = 2: full
2nd Shell = 3: not full
Bye! B
B3+ 3
2.(0)

28. Negative Ions.
These are ions formed by the atom gaining one or more electrons.
They are called anions. This is because during electrolysis they move towards the anode.
The charge on the ions is equal to the number of electrons that the atom has gained.
In equations the charge is usually shown above and to the right of the symbol. (E.g.. O2- ).
Gain 1 e- -
It is nearly always non-metal atoms that gain electrons
Ions usually have
OUTER electron shells that are either completely full or else empty
Gain 2 e- 2-
Gain 3 e- 3-

29. The Electrons in a Sulphide Ion.
In the sulphur atom
Atomic number = number of protons = 16
Number of electrons = 16 32 S 16
S2- S
2 electrons gained
Electron arrangement: (incomplete shell)
Electron arrangement (Full shells)

30. The Electrons in a Fluoride Ion.
In the fluorine atom
Atomic number = number of protons = 9
Number of electrons = 9 19 F 9
F2- F
1 electron gained
Electron arrangement: (incomplete shell)
Electron arrangement (Full shells)

31. The Oxide Ion 8 How many electrons?
Activity
The Oxide Ion 8
How many electrons?
How many electrons in the first shell?
How many electrons in the second shell?
What electron arrangement?
How many electrons to gain?
New electron arrangement? 16 O 8 2 6
2.6
1st Shell = 2: full
2nd Shell = 6: not full O
O2- 2
2.8

32. Drag the words at the top to their correct places in the sentences.

34. Word check

35. Which of the following is not a sub-atomic particle?
Proton.
Isotope.
Neutron.
Electron.

36. The element Cobalt has a relative atomic mass of 59 and an atomic number of 27. Which of these is a true statement about each neutral cobalt atom?
It contains 59 neutrons.
It contains 27 electrons.
It contains 32 protons.
It contains equal numbers of neutrons and electrons.

37. contains more protons than neutrons.
The Periodic Table displays iron as shown below. This indicates that Fe atoms:
contain 56 neutrons.
contain 30 electrons.
contain 26 protons.
contains more protons than neutrons. 56 Fe 26

38. Which of the following is true: Both isotopes contain 35 protons.
Bromine consists of a mixture of two isotopes: Bromine-79 and Bromine-81
Which of the following is true:
Both isotopes contain 35 protons.
Bromine 79 contains 46 neutrons.
Bromine 81 contains 44 neutrons.
Bromine-81 is more reactive than bromine-79. 80 Br 35

39. Natural boron consists of approx. 20% boron-10 and 80% boron-11.
What will the relative atomic mass of natural boron will be?
10.0
11.0
10.5
10.8 ? B 5

40. Which answer best describes the shell arrangement of the electrons in a sodium atom?
2,8,1.
2,2,7.
2,8,8,3.
2,8,8,1. 23 Na 11

41. Which answer best describes the shell arrangement of the electrons in an oxygen atom?
2,8,6.
2,8,8.
2,8.
2,6. 16 O 8

42. Which of these elements will have electron shells that are either full or empty (i.e. not partially full)? 14 N 7 A 40 Ar 18 B 40 Ca 20 C 27 Al 13 D

43. Which answer best describes the shell arrangement of the electrons in an oxide ion O2-?
2,8,6.
2,8,8.
2,8.
2,6. 16 O 8