Practice Test | Chapter 5 - The Structure of Matter

A molecule of water, H₂O, is held together by which type of bond?

• ionic bonds

• covalent bonds

• metallic bonds

• hydrogen bonds

Answer explanation

A molecule of water, H₂O, is formed by covalent bonds, where oxygen shares electrons with two hydrogen atoms. This sharing creates a stable structure, distinguishing it from ionic or metallic bonds.

Each molecule of carbon dioxide, CO₂, contains one atom of carbon and how many atoms of oxygen?

• one atom of oxygen

• two atoms of oxygen

• three atoms of oxygen

• four atoms of oxygen

Answer explanation

Each molecule of carbon dioxide, CO₂, consists of one carbon atom and two oxygen atoms, as indicated by the chemical formula. Therefore, the correct answer is two atoms of oxygen.

Tags

NGSS.MS-PS1-1

Atoms often bond to achieve what kind of energy state?

• a lower energy state

• a higher energy state

• a neutral charge

• a positive charge

Answer explanation

Atoms bond to achieve a lower energy state, as this configuration is more stable. By forming bonds, they can release energy, leading to a more favorable and lower energy arrangement.

Tags

NGSS.HS-PS1-1

NGSS.HS-PS1-2

In a metallic bond, electrons are:

• shared between atoms

• transferred from one atom to another

• delocalized and free to move throughout the metal

• strongly held by individual atoms

Answer explanation

In a metallic bond, electrons are delocalized, meaning they are not tied to any specific atom. This allows them to move freely throughout the metal, contributing to its conductivity and malleability.

Solid ionic compounds typically have high melting points because:

• they are soft and malleable

• they conduct electricity when solid

• the ionic bonds are strong electrostatic attractions

• they are easily dissolved in water

Answer explanation

Solid ionic compounds have high melting points because the ionic bonds are strong electrostatic attractions between oppositely charged ions, requiring significant energy to break these bonds.

Glucose, C₆H₁₂O₆, and fructose, C₆H₁₂O₆, have the same empirical formula but different:

• kinds of cations

• kinds of anions

• kinds of atoms

• molecular formulas

Answer explanation

Glucose and fructose both have the same empirical formula (C₆H₁₂O₆) but differ in their molecular structures, leading to different molecular formulas. Thus, the correct answer is 'molecular formulas'.

Magnesium has two valence electrons and oxygen has six valence electrons. The magnesium and oxygen atoms will form a(n) ________ bond by ________ their valence electrons.

• covalent, sharing

• ionic, transferring

• metallic, delocalizing

• hydrogen, sharing

Answer explanation

Magnesium donates its two valence electrons to oxygen, which needs two more to complete its octet. This transfer of electrons results in an ionic bond, as magnesium becomes positively charged and oxygen becomes negatively charged.

Tags

NGSS.HS-PS1-1

The covalent compound SO₂ would be named:

• sulfur oxide

• sulfur dioxide

• monosulfur dioxide

• disulfur monoxide

Answer explanation

The correct name for SO₂ is sulfur dioxide, as it contains one sulfur atom and two oxygen atoms. The prefix 'di-' indicates two, making 'dioxide' the appropriate term. Other options are incorrect in naming conventions.

A protein is a polymer that is made of:

• monosaccharides

• amino acids

• fatty acids

• nucleotides

Answer explanation

A protein is a polymer made of amino acids, which are the building blocks of proteins. Monosaccharides are sugars, fatty acids are components of lipids, and nucleotides are the building blocks of nucleic acids, not proteins.

Tags

NGSS.HS-LS1-6

A(n) ________ model can help you visualize a molecule's three-dimensional shape.

• ball-and-stick

• space-filling

• Lewis dot

• molecular orbital

Answer explanation

A ball-and-stick model effectively represents a molecule's three-dimensional shape by using spheres for atoms and sticks for bonds, allowing for clear visualization of molecular geometry.