1d. The Periodic Table

Question 1

Arrangement of the Periodic Table

Answer 1

There are over 100 chemical elements which have been isolated and identified
Elements are arranged on the periodic table in order of increasing atomic number
Each element has one proton more than the element preceding it
This is done so that elements end up in columns with other elements which have similar properties

Question 2

Period

Answer 2

These are the horizontal rows that show the number of shells of electrons an atom has and are numbered from 1 - 7
E.g. elements in period 2 have two electron shells, elements in period 3 have three electron shells

Question 3

Group

Answer 3

These are the vertical columns that show how many outer electrons each atom has and are numbered from 1 – 7, with a final group called group 0 (instead of group 8)
E.g. group 4 elements have atoms with 4 electrons in the outermost shell, group 6 elements have atoms with 6 electrons in the outermost shell and so on

Question 4

Deducing Electronic Configurations

Answer 4

We can represent the electronic structure of atoms using electron shell diagrams
Electrons orbit the nucleus in shells and each shell has a different amount of energy associated with it
The further away from the nucleus, the more energy a shell has
Electrons first occupy the shell closest to the nucleus which can hold a maximum of 2 electrons
When a shell becomes full of electrons, additional electrons have to be added to the next shell
The second shell and third shell can hold 8 electrons each
The outermost shell of an atom is called the valence shell and an atom is much more stable if it can manage to completely fill this shell with electrons
In most atoms, the outermost shell is not full and therefore these atoms react with other atoms in order to achieve a full outer shell of electrons (which would make them more stable)
In some cases, atoms lose electrons to entirely empty this shell so that the next shell below becomes a (full) outer shell

Question 5

Electronic Configuration of the First 20 Elements Table

Answer 5

HYDROGEN
HELIUM
LITHIUM
BERYLLIUM
BORON
CARBON
NITROGEN
OXYGEN
FLUORINE
NEON
SODIUM
MAGNESIUM
ALUMINIUM
SILICON
PHOSPHORUS
SULFUR
CHLORINE
ARGON
POTASSIUM
CALCIUM