Periodic table

• A periodic table is a listing of elements that are regulated in order of increasing atomic (proton) number.

Periods

• The elements in the periodic table are divided into periods and groups.

• Periods are horizontal rows.

• They run from left to right and there are 7 periods in total (1 to 7).

Groups

• It is a vertical column of elements.

• They run from top to bottom

• there are eight groups in total (in the periodic table).

• Group V||| is also referred as group 0.

The Periodic Trends

• The elements in the periodic table can be classified based on their metallic and non-metallic properties.

• There is an imaginary diagonal line in the periodic table. The elements located next to this line are metalloids, which means that they have the properties of both metals and non-metals.

• Metals can be found at the left side of the periodic table while the non-metals are found towards the right of the periodic table.

• Therefore, from left to right in a periodic table, there is a decrease of metallic properties and increase of non-metallic properties.

• move down a group (vertically), you will notice an increase in the metallic properties and a decrease in the non-metallic properties because the valence (outermost) electrons move far away from the nucleus and therefore, the tendency to lose electrons increases.

• The easily the metal loses electrons, the more reactive it is.

Group 1

• The elements in the group one of the periodic tables are known as the alkali metals.

• The elements in group one are:

• Lithium

• Sodium

• Pottasium

• Rubidium

• Cesium (Cs)

• Francium (Fr)

• Their melting and boiling point is low

• The metallic bonds are easily disrupted by heat

• They can be easily cut because they are soft

• They have low densities which allow them to float on water.

• Alkali metals are very reactive

• Alkali metals get oxidised and therefore, they work as strong reducing agent

• Alkali metals lose electrons and become positively charged ions.

Group 2

• Group 2A (or IIA) of the periodic table are the alkaline earth metals

• beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra).

Group 3(Transition metals)

• Scandium(Sc), Yttrium(Y), Lutetium(Lu), and Lawrencium(Lr)

• between Group 2A and Group 3A consist of Transition metals.

• high melting and boiling point

• high density

• metallic bonds are very strong and thus, high heat can overcome the forces of attraction.

• form coloured compounds and their compounds are very good catalysts.

• They are good conductors of electricity and heat.

• They are hard and have usually high densities.

• They can be hammered into different shapes.

Non metals

• Right side of the periodic table

Carbon, hydrogen, oxygen ,nitrogen

Halogens( Group V|| Elements)

• Halogens are those elements that are located in the group seven of the periodic table.

• Flourine , chlorine , bromine

• non-metals

• they have low melting and boiling point.

• move from top to bottom in the group V|||, you will notice that the boiling point increases and the colour of the elements become darker.

• Halogens are very reactive non-metals because they have seven electrons in their outermost shell.

Noble gases

• Helium, neon, argon

• inert gases (because they are un-reactive).

• colourless at room temperature

• they are monoatomic

• have stable duplet or octet electronic configuration