Which is the correct electron configuration of atomic number 18?

• 1s²2s²2p⁶3s²3p²

• 1s²2s²2p⁶3s²3p⁴4s²

• 1s²2s²2p⁶3s²3p⁶

• 1s²2s²2p⁶3s²3p³4s²

Identify the correct electron dot diagram for Lithium.

• Option A

• Option B

• Option C

• Option D

How many electrons does an atom need to be stable?

• 1

• 2

• 6

• 8

Which particle is a positively charged ion?

• Hydrogen (H) with 1 proton, 0 neutrons, and 1 electron

• Sodium (Na) with 11 protons, 12 neutrons, and 10 electrons

• Chlorine (Cl) with 17 protons, 18 neutrons, and 18 electrons

• Magnesium (Mg) with 12 protons, 12 neutrons, and 12 electrons

Which element has the electron configuration 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁷?

• Chromium

• Iron

• Manganese

• Cobalt

Which electron configuration correctly represents the ground state of bromine?

• 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁵

• 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 4d¹⁰ 4p⁵

• 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁸ 4p⁶

• 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 4d⁹ 4p⁶

The electron configuration of cesium, atomic number 55, is [Xe] 6s¹. In what period is cesium?

• Period 1

• Period 6

• Period 8

• Period 55

An ion, O²⁻, has the same electron configuration as an atom of which noble gas?

• Helium

• Neon

• Argon

• Krypton

An unknown element "Y" has the electron configuration: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹. Select any/all properties below that are characteristic of element "Y".

• Nonreactive

• Highly reactive

• Categorized as a metal

• Categorized as a nonmetal

When an atom gains electrons it will form a(n) ______.

• anion

• cation

• isotope

• molecule