Zirconium, Zr , and hafnium, Hf , are metals. The symbol for a particular ion of hafnium ion is Hf 2 + 72 180 . Deduce the number of electrons that are present in one of these hafnium ions.

For a neutral atom the number of protons and electrons will be equal. The number of protons in hafnium atom is 72, thus, the number of electrons in it will be 72. Hafnium atom loses two electrons to form Hf 2 + . Therefore, the number of electrons become 72 - 2 = 70 .

Zirconium, Zr , and hafnium, Hf , are metals. The symbol for a particular ion of hafnium ion is Hf 2 + 72 180 . Deduce the number of electrons that are present in one of these hafnium ions.

For a neutral atom the number of protons and electrons will be equal. The number of protons in hafnium atom is 72, thus, the number of electrons in it will be 72. Hafnium atom loses two electrons to form Hf 2 + . Therefore, the number of electrons become 72 - 2 = 70 .

Complete the table: Neutral atom Atomic number Nucleon number Number of each sub-atomic particle present Mg 12 24 Al 13 27

Neutral atom Atomic number Nucleon number Number of each sub-atomic particle present Mg 12 24 proton- 12, electron-12, neutron-12 Al 13 27 proton- 13, electron- 13, neutron- 14 Atomic number presents the number of protons and nucleon number represents the total number of sub-atomic particles present inside the nucleus of an atom.

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AS and A Level

IMPORTANT

Earn 100

Zirconium, $Zr$ , and hafnium, $Hf$ , are metals.

The symbol for a particular ion of hafnium ion is ${}_{72}^{180}{Hf}^{2 +}$ . Deduce the number of electrons that are present in one of these hafnium ions.

Important Questions on Atomic Structure

MEDIUM

AS and A Level

IMPORTANT

Chemistry for Cambridge International AS & A Level Coursebook with Digital Access (2 Years)>Chapter 1 - Atomic Structure>EXAM-STYLE QUESTIONS>Q 2

Zirconium, $Zr$ , and hafnium, $Hf$ , are metals.

The subatomic particles present in zirconium and hafnium are electrons, neutrons and protons. A beam of protons is fired into an electric field produced by two charged plates, as shown in the diagram.

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i) Describe how the beam of protons behaves when it passes through the gap between the charged plates.
ii) Explain your answer.

EASY

AS and A Level

IMPORTANT

Chemistry for Cambridge International AS & A Level Coursebook with Digital Access (2 Years)>Chapter 1 - Atomic Structure>EXAM-STYLE QUESTIONS>Q 2

The subatomic particles present in zirconium and hafnium are electrons, neutrons and protons. Describe and explain what happens when a beam of neutrons passes through the gap between the charged plates instead of protons in the figure:

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