Question 1:
Why are the elements sodium, Na, magnesium, Mg, aluminium, Al, silicon, Si, phosphorus, P, sulphur, S, chlorine, Cl and argon, Ar in the same period?
Answer:
These elements have three electron shells. Sodium, Na (2.8.1), magnesium, Mg (2.8.2), aluminium, Al (2.8.3), silicon, Si (2.8.4), phosphorus, P (2.8.5), sulphur, S (2.8.6), chlorine, Cl (2.8.7) and argon, Ar (2.8.8).
Why are the elements sodium, Na, magnesium, Mg, aluminium, Al, silicon, Si, phosphorus, P, sulphur, S, chlorine, Cl and argon, Ar in the same period?
Answer:
These elements have three electron shells. Sodium, Na (2.8.1), magnesium, Mg (2.8.2), aluminium, Al (2.8.3), silicon, Si (2.8.4), phosphorus, P (2.8.5), sulphur, S (2.8.6), chlorine, Cl (2.8.7) and argon, Ar (2.8.8).
Question 2:
Silicon exists as a solid at room temperature while non-metals like chlorine exists as a gas.
Explain.
Answer:
Silicon has high melting point and boiling point. Chlorine has low melting point and boiling point.
(Student’s suitable answer)
Silicon exists as a solid at room temperature while non-metals like chlorine exists as a gas.
Explain.
Answer:
Silicon has high melting point and boiling point. Chlorine has low melting point and boiling point.
(Student’s suitable answer)
Question 3:
Figure 4.15 shows several elements in the Periodic Table of Elements.
(a) When aluminium and chlorine are compared, which element has a smaller atomic size?
Explain.
(b) Which element forms an amphoteric oxide?
(c) Arrange all the elements in accending order of atomic size.
Answer:
(a) Chlorine, Cl has smaller atomic size than aluminium. This is because when going across Period 3 from left to right, the number of shells is the same but the number of protons in the atom increases.
This causes the nuclear attraction towards the electron to increase and causes the atomic radius to decrease. Hence, the size of the atom decreases.
(b) Aluminium, Al
(c) Ne, C, Cl, Al, Na
Figure 4.15 shows several elements in the Periodic Table of Elements.
(a) When aluminium and chlorine are compared, which element has a smaller atomic size?
Explain.
(b) Which element forms an amphoteric oxide?
(c) Arrange all the elements in accending order of atomic size.
Answer:
(a) Chlorine, Cl has smaller atomic size than aluminium. This is because when going across Period 3 from left to right, the number of shells is the same but the number of protons in the atom increases.
This causes the nuclear attraction towards the electron to increase and causes the atomic radius to decrease. Hence, the size of the atom decreases.
(b) Aluminium, Al
(c) Ne, C, Cl, Al, Na