Metals and Non-metals Past Paper PDF

→ Mg 2+ + 2e – Mg  2, 8, 2 2, 8 (Magnesium cation) Cl +e – ...

→ Mg 2+ + 2e – Mg  2, 8, 2 2, 8 (Magnesium cation) Cl +e –  → Cl – 2,8,7 2,8,8 (Chloride anion) Figure 3.6 Formation of magnesium chloride The compounds formed in this manner by the transfer of electrons from a metal to a non-metal are known as ionic compounds or electrovalent compounds. Can you name the cation and anion present in MgCl2? 3.3.1 Properties of Ionic Compounds To learn about the properties of ionic compounds, let us perform the following Activity: Activity 3.13 n Take samples of sodium chloride, potassium iodide, barium chloride or any other salt from the science laboratory. n What is the physical state of these salts? n Take a small amount of a sample on a metal spatula and heat directly on the flame (Fig. 3.7). Repeat with other samples. n What did you observe? Did the samples impart any colour to the flame? Do these compounds melt? n Try to dissolve the samples in water, petrol and kerosene. Figure 3.7 Are they soluble? Heating a salt sample on a n Make a circuit as shown in Fig. 3.8 and insert the electrodes spatula into a solution of one salt. What did you observe? Test the other salt samples too in this manner. n What is your inference about the nature of these compounds? Table 3.4 Melting and boiling points of some ionic compounds I onic Melting point Boiling point compound (K) (K) NaCl 1074 1686 LiCl 887 1600 CaCl2 1045 1900 Figure 3.8 CaO 2850 3120 Testing the conductivity of MgCl2 981 1685 a salt solution 48 Science 2024-25