Question 1:
How did Moseley arrange the elements in the Periodic Table of Elements?
Answer:
According to increase in proton number
How did Moseley arrange the elements in the Periodic Table of Elements?
Answer:
According to increase in proton number
Question 2:
Figure 1 shows the chemical symbol for element X.
(a) Which group does element X belong to in the Periodic Table of Elements?
(b) Which period does element X belong to in the Periodic Table of Elements?
Answer:
(a) Group 17
(b) Period 3
Figure 1 shows the chemical symbol for element X.
(a) Which group does element X belong to in the Periodic Table of Elements?
(b) Which period does element X belong to in the Periodic Table of Elements?
Answer:
(a) Group 17
(b) Period 3
Question 3:
A restaurant owner uses colourful electric lights to attract his customers. What is the substance suitable for making such lights?
Answer:
Neon
A restaurant owner uses colourful electric lights to attract his customers. What is the substance suitable for making such lights?
Answer:
Neon
Question 4:
State the physical and chemical properties of the element with electron arrangement 2.8.8.1.
Answer:
This element is a shiny grey, soft metal. Group 1 elements react vigorously with oxygen, water and chlorine gas.
State the physical and chemical properties of the element with electron arrangement 2.8.8.1.
Answer:
This element is a shiny grey, soft metal. Group 1 elements react vigorously with oxygen, water and chlorine gas.
Question 5:
State the element in Period 3 that forms an amphoteric oxide.
Answer:
Aluminium
State the element in Period 3 that forms an amphoteric oxide.
Answer:
Aluminium
Question 6:
Figure 2 shows several elements in the Periodic Table of Elements that are represented by alphabets X and Y.
(a) Write the electron arrangement for atom X and atom Y.
(b) Explain two differences in chemical properties between element X and element Y.
(c) Why does the reactivity of elements in the same group as X, increase when going down the group, but the reactivity of elements in the same group as Y decreases?
Answer:
(a) Electron arrangement of X = 2.2
Electron arrangement of Y = 2.8.7
(b)
(c)
• The reactivity of an element that is in the same group as Element X depends on the tendency of the atom to lose two electrons
• When going down the group, the increasing size of the atom causes the distance between the nucleus and the valence electrons to increase
• The nuclear attraction towards the valence electrons become weaker
• It is easier for the atom to lose electrons. Hence, the reactivity of the element increases when going down the group.
• The reactivity of an element that is in the same group as Element Y depends on the tendency of the atom to receive or pull one electron.
• When going down the group, the increasing size of the atom causes the distance between the nucleus and the valence electrons to increase.
• The nuclear attraction towards the valence electrons become weaker
• It is harder for the atom to receive or attract electrons. Hence, the reactivity of the element decreases when going down the group.
Figure 2 shows several elements in the Periodic Table of Elements that are represented by alphabets X and Y.
(a) Write the electron arrangement for atom X and atom Y.
(b) Explain two differences in chemical properties between element X and element Y.
(c) Why does the reactivity of elements in the same group as X, increase when going down the group, but the reactivity of elements in the same group as Y decreases?
Answer:
(a) Electron arrangement of X = 2.2
Electron arrangement of Y = 2.8.7
(b)
(c)
• The reactivity of an element that is in the same group as Element X depends on the tendency of the atom to lose two electrons
• When going down the group, the increasing size of the atom causes the distance between the nucleus and the valence electrons to increase
• The nuclear attraction towards the valence electrons become weaker
• It is easier for the atom to lose electrons. Hence, the reactivity of the element increases when going down the group.
• The reactivity of an element that is in the same group as Element Y depends on the tendency of the atom to receive or pull one electron.
• When going down the group, the increasing size of the atom causes the distance between the nucleus and the valence electrons to increase.
• The nuclear attraction towards the valence electrons become weaker
• It is harder for the atom to receive or attract electrons. Hence, the reactivity of the element decreases when going down the group.