Review Quiz

Which of the following elements has the highest electronegativity?

• Fluorine

• Nitrogen

• Chlorine

• Oxygen

Answer explanation

Fluorine has the highest electronegativity of all elements, with a value of 3.98 on the Pauling scale. This makes it the most effective at attracting electrons in a chemical bond compared to nitrogen, chlorine, and oxygen.

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Electronegativity is the ability of an atom to attract electrons in a bond. Why is fluorine more electronegative than oxygen?

• Oxygen is more electronegative due to its position in the periodic table.

• Fluorine has fewer protons than oxygen.

• Fluorine has more protons to attract electrons.

• Oxygen has a larger atomic radius than fluorine.

Answer explanation

Fluorine is more electronegative than oxygen because it has more protons in its nucleus, which increases its ability to attract electrons in a bond. This greater positive charge leads to a stronger pull on the bonding electrons.

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Which of the following pairs of atoms is most likely to form an ionic bond?

• Hydrogen and Helium

• Sodium and Oxygen

• Calcium and Fluorine

• Sodium and Chlorine

Answer explanation

Sodium and Chlorine are both highly reactive; Sodium (Na) has one electron in its outer shell and Chlorine (Cl) has seven. Sodium can easily lose its electron, while Chlorine can gain one, leading to the formation of an ionic bond.

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Which of the following ions has a charge of +2?

• Cl^-

• Na⁺

• K⁺

• Ca²⁺

Answer explanation

The ion Ca²⁺ has a charge of +2, indicating it has lost two electrons. In contrast, Cl^- has a -1 charge, while Na⁺ and K⁺ both have a +1 charge.

Why does an atom of sodium (Na) form a Na⁺ ion?

• Na⁺ is formed by combining sodium with chlorine.

• An atom of sodium forms a Na⁺ ion by losing one electron from its outer shell.

• Sodium forms a Na⁺ ion by splitting its nucleus.

• An atom of sodium gains an electron to become Na⁻.

Answer explanation

An atom of sodium forms a Na⁺ ion by losing one electron from its outer shell. This loss of an electron allows sodium to achieve a stable electron configuration, similar to that of noble gases.

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Which of the following ionic compounds is correctly formed by combining ions with the appropriate charges?

• NaCl

• KP

• MgKr

• CaHe

Answer explanation

NaCl is formed by combining Na+ (sodium) and Cl- (chloride) ions, which have charges that balance each other. The other options do not represent valid ionic compounds due to incorrect ion combinations.

If you combine a magnesium ion (Mg²⁺) and a chloride ion (Cl⁻) to form an ionic compound, what is the simplest formula of the compound?

• MgCl

• Mg₂Cl

• MgCl₃

• MgCl₂

Answer explanation

The magnesium ion (Mg²⁺) has a +2 charge, while the chloride ion (Cl⁻) has a -1 charge. To balance the charges, two chloride ions are needed for each magnesium ion, resulting in the formula MgCl₂.

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You are given two elements: X (with a charge of +3) and Y (with a charge of -1). What is the formula for the ionic compound they would form?

• XY₃

• X₂Y

• XY₄

• XY

Answer explanation

To form an ionic compound, the total positive charge must balance the total negative charge. X has a charge of +3 and Y has a charge of -1. To balance, we need 3 Y ions for every X ion, resulting in the formula XY₃.

How strongly an atom attracts electrons is called....................

• Ionization energy

• Electronegativity

• Electricity

• Nuclear force

Answer explanation

Electronegativity measures how strongly an atom attracts electrons in a chemical bond. It is a key concept in understanding chemical reactivity and bonding, distinguishing it from ionization energy, which refers to removing electrons.

What is the same within each group on the periodic table?

• Number of electrons

• Number of valence electrons

• Number of atoms

Answer explanation

In each group of the periodic table, elements have the same number of valence electrons, which determines their chemical properties. This is why 'Number of valence electrons' is the correct answer.

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