Unit 5

Front

Valence electrons are involved in the formation of a chemical bond.

Back

True

Answer explanation

True. Valence electrons are the outermost electrons of an atom and play a crucial role in forming chemical bonds by being shared or transferred between atoms.

Front

Chemical bond formed from the electrostatic attraction between positive and negative ions

Back

ionic bond

Answer explanation

An ionic bond is formed through the electrostatic attraction between positively charged ions (cations) and negatively charged ions (anions). This distinguishes it from covalent and metallic bonds.

Front

When 2 atoms share electrons

Back

covalent bond

Answer explanation

When 2 atoms share electrons, they form a covalent bond. This type of bond allows atoms to achieve stability by filling their outer electron shells through shared pairs of electrons.

Front

In the electron sea model of a metallic bond

Back

mobile electrons are shared by all atoms

Answer explanation

In the electron sea model, metallic bonding involves mobile electrons that are not fixed to any specific atom. These delocalized electrons are shared among all atoms, allowing for conductivity and malleability, making this choice correct.

Front

A substance has a low boiling point and does not conduct electricity. Possible substance: Fe, NaCl, NH₃.

Back

NH₃

Answer explanation

NH3 (ammonia) has a low boiling point and does not conduct electricity in its pure form, as it is a molecular compound. In contrast, Fe (iron) is a metal and conducts electricity, while NaCl (sodium chloride) is an ionic compound that conducts when dissolved.

Front

Example of an IONIC COMPOUND: NaCl, H₂O, CO₂, NO

Back

NaCl

Answer explanation

NaCl, or sodium chloride, is an ionic compound formed from the electrostatic attraction between positively charged sodium ions and negatively charged chloride ions. The other options are molecular compounds.

Front

Characteristic property of ionic compounds?

Back

They form hard, brittle crystals with characteristic shapes

Answer explanation

Ionic compounds are characterized by forming hard, brittle crystals with distinct shapes due to the strong electrostatic forces between charged ions. This property distinguishes them from substances with low melting and boiling points.

Front

What is the correct name for CaBr₂?

Back

Calcium Bromide

Answer explanation

The correct name for CaBr2 is Calcium Bromide. In ionic compounds, the cation (Calcium) is named first, followed by the anion (Bromide). Therefore, Calcium Bromide is the proper nomenclature.

Front

The chemical formula of carbon tetrachloride is

Back

CCl₄

Answer explanation

The correct chemical formula for carbon tetrachloride is CCl₄, indicating one carbon atom and four chlorine atoms. The other options do not accurately represent the composition of carbon tetrachloride.

Front

The chemical formula of dinitrogen tetroxide is

Back

N₂O₄

Answer explanation

Dinitrogen tetroxide is represented by the formula N₂O₄, indicating it contains two nitrogen (N) atoms and four oxygen (O) atoms. The other options do not correspond to this compound.