Chemical Bonding & Extended Structures

A particle of aluminum is found to have 13 protons in its nucleus with 10 electrons in orbit around the nucleus. This particle would be

• negatively charged

• positively charged

• electrically neutral

• heavier than a normal aluminum atom

Answer explanation

The particle has 13 protons (positive charge) and 10 electrons (negative charge). The net charge is +3, making it positively charged.

Tags

NGSS.HS-PS1-1

Which diagram represents an ion?

• Option A

• Option B

• Option C

• Option D

Answer explanation

Option C represents an ion because it shows a charged particle, indicating a loss or gain of electrons. Ions are characterized by their charge, which is clearly depicted in this diagram.

An atom of calcium loses 2 electrons in forming a chemical compound. The charge on the resulting calcium ion is

• 1+

• 2+

• 1–

• 2–

Answer explanation

Calcium (Ca) has 20 electrons. When it loses 2 electrons, it has 18 electrons left, resulting in a net positive charge of 2. Therefore, the charge on the resulting calcium ion is 2+.

Tags

NGSS.HS-PS1-1

NGSS.HS-PS1-2

Atoms become positive ions by

• gaining electrons

• sharing electrons

• losing electrons

• gaining protons

Answer explanation

Atoms become positive ions by losing electrons. When an atom loses one or more electrons, it has more protons than electrons, resulting in a net positive charge.

Tags

NGSS.HS-PS1-2

As an Na atom forms an Na⁺ ion, the number of protons in its nucleus

• decreases

• increases

• remains the same

Answer explanation

As an Na atom loses an electron to form an Na⁺ ion, it becomes positively charged. However, the number of protons in the nucleus remains the same, as protons define the element. Therefore, the correct answer is that the number of protons remains the same.

Which type of bond is formed by the sharing of electrons between atoms?

• a covalent bond

• a hydrogen bond

• metallic bond

• an ionic bond

Answer explanation

A covalent bond is formed when two atoms share electrons, allowing them to achieve stability. This distinguishes it from hydrogen bonds, metallic bonds, and ionic bonds, which involve different interactions.

Tags

NGSS.HS-PS1-1

Which is a property of ionic substances?

• insoluble in water

• a high melting point

• malleability

• usually exist as liquids and gases at room temperature

Answer explanation

Ionic substances are characterized by strong electrostatic forces between ions, resulting in a high melting point. They are typically soluble in water and exist as solids at room temperature, not as liquids or gases.

Which compound contains covalent bonds?

• NaCl

• CaCl₂

• MgO

• CO₂

Answer explanation

CO₂ contains covalent bonds between carbon and oxygen atoms, where electrons are shared. In contrast, NaCl, CaCl₂, and MgO are ionic compounds, formed by the transfer of electrons.

Which of the following compounds is an ionic compound?

• KF

• HBr

• CO

• NO

Answer explanation

KF is an ionic compound because it consists of potassium (K) and fluorine (F), which form ions (K+ and F-). In contrast, HBr, CO, and NO are covalent compounds, formed by sharing electrons.

When ionic bonds are formed, metal atoms tend to

• lose electrons and become negative ions

• lose electrons and become positive ions

• gain electrons and become negative ions

• gain electrons and become positive ions

Answer explanation

When ionic bonds form, metal atoms lose electrons, resulting in a positive charge. This is because they have fewer electrons than protons, making them positive ions. Therefore, the correct choice is to lose electrons and become positive ions.