The periodic table

Question 1

What is the periodic table?

Answer 1

The periodic table is a table in which the chemical elements are arranged in order of increasing atomic number. Elements with similar properties are arranged in the same column (called a group), and elements with the same number of electron shells are arranged in the same row (called a period).

Question 2

Rules for writing element symbols

Answer 2

Each element on the periodic table has a symbol made of 1 or two letters.

• The first letter is always a capital e.g. N for Nitrogen, C for Carbon, O for Oxygen
• If there are two letters in an element symbol, the second is always lowercase e.g. Co for Coblat, Mg for Magnesium, Ne for Neon

Question 3

Atomic Numbers and Atomic Mass

Answer 3

With each element symbol there are two numbers that are based on the number of sub-atomic particles (protons, neutrons, electrons):

1. Atomic Number - Tells us the number of electrons/protons. (It is the smaller number).
   - atomic number is the number of protons rather than electrons, as atoms can gain or lose electrons, changing the number they have
2. Atomic Mass - The number of protons + neutrons. (It is the larger number)

• The atoms of any particular element always contain the same number of protons eg magnesium always contains 12 protons

Question 4

How to locate elements on the periodic table by name or symbol?

Answer 4

On the periodic table, elements are listed in order of increasing atomic number. Elements in the same row are in the same period. This means they have similar physical properties, such as how well they bend or conduct electricity. Elements in the same column are in the same group. This means they react with other elements in similar ways.

Question 5

How to work out the number of neutrons?

Answer 5

Atomic mass - number of protons/ atomic number
= number of neutrons

Question 6

How to identify the chemical symbol and name of an element using the Periodic Table?

Answer 6

The first letter of the symbol is usually the first letter of the element’s name, while the second letter is some other letter from the name.

Question 7

How is the Periodic Table organised in Groups (columns) and Periods (rows)?

Answer 7

The periodic table is organized into groups (vertical columns), periods (horizontal rows), and families (groups of elements that are similar). Elements in the same group have the same number of valence electrons, and elements in the same period have the same number of occupied electron shells.

Question 8

What are valance electrons?

Answer 8

Valance electrons are the electrons on the outermost shell of an atom. The group number an element is in tells us how may valance/ outside shell electrons an element has.

Eg Sodium is in group 1, it has 1 valance electron.