Science : Ch 03 – Metals and Non-metals

Na (sodium) and Ca (calcium) react vigorously with water. Mg (magnesium) respond with water less vigorously than calcium and sodium. Fe (iron), on the other hand, does not react with cold as well as hot water instantly.

Because it is a covalent compound formed by sharing of electrons. Whereas in other three compounds are ionic compounds and they conduct electricity in their molten state.

Prolong heating of red hot iron with steam forms Fe₃O₄ with hydrogen gas.

Ionic compounds are generally soluble in water and insoluble in solvents such as kerosene and petrol.

Ionic compounds conduct electricity when molten (liquid) or in aqueous solution (dissolved in water), for that reason their ions are free to move from place to place. In solid state, no free or mobile ions are available for conducting electricity

At room temperature, mercury (Hg) is the only metal found in liquid state.

Magnesium metal never reacts with cold water but reacts with both hot water and steam to form magnesium hydroxide and hydrogen gas.

Na (sodium) possesses all the above properties. It is too soft and can be cut with a knife.. It also reacts with water and burns due to the vigorously formation of hydrogen gas.

Some of the metals like aluminium (Al) metal forms amphoteric oxide (Al₂O₃), which can behave like acid as well as base.

When calcium is treated with water, it reacts vigorously with water and to produce a cloudy white precipitate of calcium_x000D_hydroxide and hydrogen gas is released as bubbles

HCl is a polar covalent compound and CCl₄  is a non-polar covalent compound. besides, sodium chloride (NaCl) and potassium chloride (KCl) form ionic compounds, as they consist of positive and negative ions.