5-8 Valence Electrons

What does an electron configuration describe?

• The arrangement of electrons in an atom’s orbitals
• The number of neutrons in an atom
• The size of an atom
• The reactivity of an atom

Answer explanation

Electron configurations show how electrons are distributed among orbitals.

Tags

NGSS.HS-PS1-1

NGSS.HS-PS1-2

What does the superscript in an electron configuration indicate?

• The number of electrons in a sublevel
• The energy level of the orbital
• The type of sublevel (s, p, d, f)
• The atomic number of the atom

Answer explanation

Superscripts represent the number of electrons in a given sublevel.

Which element has the electron configuration 1s²?

• Helium
• Hydrogen
• Lithium
• Beryllium

Answer explanation

Helium has two electrons, filling the 1s sublevel.

Tags

NGSS.HS-PS1-1

What is the electron configuration for carbon (C)?

• 1s² 2s² 2p²
• 1s² 2s² 2p³
• 1s² 2p²
• 1s² 2s²

Answer explanation

Carbon has 6 electrons, distributed as 1s² 2s² 2p².

Tags

NGSS.HS-PS1-1

How many electrons can fit in an s sublevel?

• 2.0
• 4.0
• 6.0
• 8.0

Answer explanation

The s sublevel can hold a maximum of 2 electrons.

Which sublevel starts filling after 2p?

• 3s
• 3p
• 2d
• 2s

Answer explanation

According to the order of fill, 3s follows 2p.

What does the periodic table’s first period correspond to?

• 1 principal energy level
• 2 sublevels
• 3 electrons
• 1 neutron

Answer explanation

The first period represents the first energy level (1s).

Tags

NGSS.HS-PS1-1

What element has the electron configuration 1s² 2s² 2p⁵?

• Fluorine
• Oxygen
• Neon
• Nitrogen

Answer explanation

Fluorine has 9 electrons, with this configuration.

Tags

NGSS.HS-PS1-1

How are elements in the second period arranged?

• By filling the 2s and 2p sublevels
• By filling the 3s sublevel
• By filling the 1s sublevel
• By filling the 4d sublevel

Answer explanation

Elements in the second period fill the 2s and 2p sublevels.

Tags

NGSS.HS-PS1-1

Which electron configuration belongs to neon (Ne)?

• 1s² 2s² 2p⁶
• 1s² 2s² 2p⁵
• 1s² 2s² 2p⁴
• 1s² 2s² 3s¹

Answer explanation

Neon has a filled 2p sublevel: 1s² 2s² 2p⁶.

Tags

NGSS.HS-PS1-1