A level atomic structure

How many protons, electrons, and neutrons, respectively, does this species have?

• 15, 15, 16

• 15, 12, 16

• 15, 18, 16

• 15, 12, 27

Answer explanation

The species has 15 protons (atomic number), 18 electrons (indicating a -3 charge), and 16 neutrons (mass number 31 - protons). Thus, the correct answer is 15 protons, 18 electrons, and 16 neutrons.

Non transition elements (elements in the tall columns of the periodic table) tend to:

• have high ionization energies

• have high metallic character

• gain or lose electrons to remain neutral

• gain or lose electrons to become isoelectronic with a noble gas

Answer explanation

Non-transition elements typically gain or lose electrons to achieve a stable electron configuration, often becoming isoelectronic with noble gases, which have full valence shells.

Which of the following would represent an atom containing 26 protons, 24 electrons and 30 neutrons?

• ⁵⁶Fe²⁺

• ⁵⁶Cr²⁺

• ⁵⁶Fe^2-

• ³⁰Fe²⁺

Answer explanation

The atom has 26 protons (Fe), 24 electrons (indicating a +2 charge), and a mass number of 56 (26 protons + 30 neutrons). Thus, it is represented as \(^{56}Fe^{2+}\).

How many dots would you place on the outer energy level dot cross structure for Phosphorus?

• 15

• 3

• 5

• 31

Answer explanation

Phosphorus has 5 valence electrons, which are represented as dots in the outer energy level dot cross structure. Therefore, you would place 5 dots for Phosphorus.

Which one is a valid orbital diagram?

• b.

• c.

• d.

• e.

Answer explanation

Choice e is a valid orbital diagram as it correctly represents the distribution of electrons in atomic orbitals, following the Pauli exclusion principle and Hund's rule. The other options do not adhere to these principles.

How many unpaired electrons are in the electron configuration for Chromium?

• 1

• 3

• 4

• 6

Answer explanation

Chromium has the electron configuration [Ar] 3d5 4s1. It has 5 unpaired electrons in the 3d subshell and 1 in the 4s subshell, totaling 6 unpaired electrons.

The electron configuration for an atom of potassium is:

• 1s²2s²2p⁶3s²3p³

• 1s²2s²2p⁶3s²3p⁶

• 1s²2s²2p⁶3s²3p⁶4s¹

• 1s²2s²2p⁶3s²3p⁶4s²

Answer explanation

The correct electron configuration for potassium (K, atomic number 19) is 1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹. This shows that potassium has one electron in the 4s subshell after filling the lower energy levels.

Use an electron configuration to determine the total number of electrons in the 3rd energy level in a titanium atom.

• 2

• 4

• 10

• 18

Answer explanation

Titanium has an atomic number of 22, with the electron configuration of 1s² 2s² 2p⁶ 3s² 3p⁶. The 3rd energy level (n=3) contains 2 electrons in 3s and 6 in 3p, totaling 10 electrons.

How many electrons can a "d" orbital hold?

• 2

• 6

• 10

• 14

Answer explanation

A 'd' orbital can hold a maximum of 10 electrons, but the question asks for how many electrons can be in a single 'd' orbital. Each 'd' orbital can hold 2 electrons, making the correct answer 2.

Halogens have how many valence (outer shell) electrons?

• 1

• 7

• 8

• 17

Answer explanation

Halogens, which include elements like fluorine and chlorine, have 7 valence electrons in their outer shell. This is why they are highly reactive, as they seek to gain one more electron to achieve a stable octet.