A) Complete the table...i) X (Neutron number for A) ...ii) Y (Electron number for B) ...iii) Z (Mass number for C). b) Elements A and B are involved in bonding. i) Give the formula of the compound for

Here are the solutions to Question 1:

Question 1:

a) Complete the table above by giving the values of

Step 1: Use the relationships: Atomic Number = Proton Number, Mass Number = Proton Number + Neutron Number, and for a neutral atom, Electron Number = Proton Number.

• i) X (Neutron number for A):

  $$\text{Mass Number} = \text{Proton Number} + \text{Neutron Number}$$ $$35 = 17 + X$$ $$X = 35 - 17 = 18$$

  i) $\boxed{18}$

• ii) Y (Electron number for B): For a neutral atom, Electron Number = Proton Number.

  $$Y = 12$$

  ii) $\boxed{12}$

• iii) Z (Mass number for C):

  $$\text{Mass Number} = \text{Proton Number} + \text{Neutron Number}$$ $$Z = 3 + 4 = 7$$

  iii) $\boxed{7}$

b) Elements A and B are involved in bonding

• i) Give the formula of the compound formed. Element A has 17 protons (Chlorine, Cl) and an electronic configuration of 2, 8, 7. It tends to gain 1 electron to form $\text{A}^-$. Element B has 12 protons (Magnesium, Mg) and an electronic configuration of 2, 8, 2. It tends to lose 2 electrons to form $\text{B}^{2+}$. To balance the charges, one $\text{B}^{2+}$ ion combines with two $\text{A}^-$ ions. i) The formula of the compound formed is $\boxed{\text{BA}_2}$ (or $\boxed{\text{MgCl}_2}$).

• ii) Name the type of bond involved. Since element B (a metal) transfers electrons to element A (a non-metal), the bond formed is ionic. ii) The type of bond involved is $\boxed{\text{Ionic bond}}$.

c) Give the electronic configuration of elements

• i) A: Element A has an atomic number of 17. i) The electronic configuration of A is $\boxed{2, 8, 7}$.

• ii) D: Element D has an atomic number of 8. ii) The electronic configuration of D is $\boxed{2, 6}$.

e) To which group of the Periodic Table does elements C and D fall?

• i) C: Element C has an atomic number of 3. Its electronic configuration is 2, 1. It has 1 valence electron. i) Element C falls in $\boxed{\text{Group 1}}$ (Alkali metals).

• ii) D: Element D has an atomic number of 8. Its electronic configuration is 2, 6. It has 6 valence electrons. ii) Element D falls in $\boxed{\text{Group 16}}$ (or Group VI/Chalcogens).

f) How would the element C be stored in the laboratory?

Element C (Lithium) is an alkali metal, which is highly reactive with oxygen and moisture in the air.

f) Element C would be stored $\boxed{\text{under oil (e.g., paraffin oil) or in an inert atmosphere}}$.