What atom matches this electron configuration?
1s²2s²2p⁶3s²3p⁶4s²3d¹⁰

• Zinc

• Copper

• Nickel

• Germanium

Answer explanation

The electron configuration 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ corresponds to Zinc (Zn), which has an atomic number of 30. This configuration indicates a complete filling of the first three shells and the 3d subshell.

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The electron configuration of an atom is 1s²2s²2p⁶.  The number of electrons in the atom is 

• 3

• 6

• 8

• 10

Answer explanation

The electron configuration 1s²2s²2p⁶ indicates there are 2 electrons in the 1s subshell, 2 in the 2s, and 6 in the 2p. Adding these gives 2 + 2 + 6 = 10 electrons in total, making the correct answer 10.

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What is the electron configuration of Iodine?

• [Kr]5s²4d¹⁰5p⁶

• [Kr]5s²5d¹⁰5p⁵

• [Kr]5s²5d¹⁰6p⁶

• [Kr]5s²4d¹⁰5p⁵

Answer explanation

Iodine has an atomic number of 53. Its electron configuration is [Kr] 5s² 4d¹⁰ 5p⁵, indicating it has 5 electrons in the 5p subshell, making the correct choice [Kr]5s²4d¹⁰5p⁵.

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Which of the following ions does not have the same number of electrons as Krypton, Kr?

• Se^-2

• Sr^-2

• Rb⁺

• As^-3

Answer explanation

Krypton (Kr) has 36 electrons. Se^-2 has 34, Rb⁺ has 36, and As^-3 has 36. However, Sr^-2 has 38 electrons, which is more than Krypton, making it the correct choice.

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What is a valence electron?

• an electron that is found in the outermost shell of an atom. 

• an electron found in the innermost shell of an atom.

• an electron found in the middle shell.

Answer explanation

A valence electron is an electron that is found in the outermost shell of an atom. These electrons are crucial for chemical bonding and determine the reactivity of the element.

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What is the number of valence electrons for Oxygen?

• 8

• 6

• 2

• 1

Answer explanation

Oxygen has 6 valence electrons, which are found in its outer shell. This is because it is in group 16 of the periodic table, where elements typically have 6 valence electrons.

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How many valence electrons does calcium have?

• 2

• 4

• 6

• 7

Answer explanation

Calcium is in group 2 of the periodic table, which means it has 2 valence electrons. This is the correct choice, as elements in this group typically lose 2 electrons to form positive ions.

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How many valence electrons are in this electron configuration? 1s²2s²2p⁶3s²3p⁴

• 4

• 6

• 2

• 8

Answer explanation

The given electron configuration ends in 3s²3p⁴. The valence electrons are those in the outermost shell, which are 2 (from 3s) + 4 (from 3p) = 6. Therefore, the correct answer is 6.

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What do atoms that form positive ions tend to do?

• lose electrons 

• lose protons

• gain electrons

• gain protons

Answer explanation

Atoms that form positive ions tend to lose electrons. This loss occurs because they have fewer electrons than protons, resulting in a net positive charge.

When is an atom stable?

• when it has a half-filled valence shell

• when it has a full valence electron shell

• when it has an empty valence electron shell

• when it is neutral

Answer explanation

An atom is stable when it has a full valence electron shell, as this configuration minimizes energy and maximizes stability. Atoms with full shells are less likely to react with others.

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