Atomic Structure

What is the electronic configuration of Mg²⁺?

• 1s² 2s² 2p⁶

• 1s² 2s² 2p⁶ 3s²

• 1s² 2s² 2p⁶ 3s² 3p²

• 1s² 2s² 2p⁶ 3s² 3p⁶ 3d² 4s²

Which atom has its outermost electron in an orbital of the shape shown, with principal quantum number 3?

• sodium

• chlorine

• calcium

• bromine

Which atom has the same number of electrons as the hydroxide ion, OH^–?

• F

• Ne

• Na

• Mg

This question refers to isolated gaseous atoms in the ground state. In which atom are all electrons paired?

• Ba

• Br

• S

• Si

Which atom has exactly three unpaired electrons in the ground state?

• an isolated gaseous aluminium atom

• an isolated gaseous carbon atom

• an isolated gaseous chromium atom

• an isolated gaseous phosphorus atom

Which statement about the electrons in a ground state carbon atom is correct?

• Electrons are present in four different energy levels

• There are more electrons in p orbitals than there are in s orbitals

• The occupied orbital of highest energy is spherical

• The occupied orbital of lowest energy is spherical

The table shows the numbers of protons, neutrons and electrons in four different particles, W, X, Y, and Z. Which pair represents the atoms of two isotopes of the same element?

• W and Y

• W and Z

• X and Y

• X and Z

Where in the Periodic Table is the element that has an outer electron shell arrangement of 4s² 4p³?

• A

• B

• C

• D

In which pair of species do both species have only one unpaired p electron?

• Ar⁺ and C^–

• B and Ti⁺

• F and Ga

• Se^– and Si

The ion X²⁺ has the same electronic configuration as the atom Kr. What is the electronic configuration of an atom of X?

• A

• B

• C

• D