Structure of Matter

Diamond and graphite are both solids made up of carbon atoms. Why is graphite softer than diamonds?

• They are different states of matter.

• Graphite is a compound and diamond is an element.

• Graphite is made up of more than one type of element.

• The arrangement of atoms vary in each substance.

Answer explanation

Graphite and diamond are both forms of carbon, but their properties differ due to the arrangement of atoms. In graphite, carbon atoms are arranged in layers that can slide over each other, making it softer, while diamond has a rigid, strong structure.

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NGSS.MS-PS1-1

Which of the following is made up of extended structures with repeated subunits?

• Crystals

• Atom

• Helium

• Neutron

Answer explanation

Crystals are made up of extended structures with repeated subunits, known as unit cells, which form a regular pattern. In contrast, atoms, helium, and neutrons are not structured in this way.

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NGSS.MS-PS1-1

A state of matter with a definite volume and shape

• Atom

• Solid

• Crystal

• Substance

Answer explanation

A solid is a state of matter characterized by a definite volume and shape, unlike liquids and gases. Atoms in a solid are closely packed, giving it a fixed structure, making 'Solid' the correct answer.

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NGSS.MS-PS1-4

The building blocks of all matter; the smallest unit that retains the chemical properties of an element

• Crystal

• Substance

• Atom

• Solid

Answer explanation

The correct answer is 'Atom' because it is the smallest unit of matter that retains the chemical properties of an element, unlike 'Crystal', 'Substance', or 'Solid', which refer to larger structures or categories.

Tags

NGSS.MS-PS1-1

Molecule

• Any form of matter that is uniform throughout and has consistent properties

• Solid material whose atoms, molecules, or ions are arranged in an ordered pattern

• The building blocks of all matter; the smallest unit that retains the chemical properties of an element

• Two or more atoms held strongly together by covalent bonds

Answer explanation

A molecule is defined as two or more atoms held strongly together by covalent bonds, making this the correct choice. Other options describe different concepts in chemistry, such as matter or solid structures.

Tags

NGSS.MS-PS1-1

Which of the following models could represent a water molecule (H₂O)?

• H-H-O-O

• H-H-O

• H-O-O

• H-H

Answer explanation

The correct model for a water molecule (H2O) is H-H-O, which shows two hydrogen atoms bonded to one oxygen atom. The other options either have incorrect atom counts or arrangements.

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NGSS.MS-PS1-1

Crystal

• Solid material whose atoms, molecules, or ions are arranged in an ordered pattern

• The building blocks of all matter; the smallest unit that retains the chemical properties of an element

• Two or more atoms held strongly together by covalent bonds

• A state of matter with a definite volume and shape

Answer explanation

A crystal is defined as a solid material with a highly ordered arrangement of atoms, molecules, or ions. This distinguishes it from other forms of matter, making the first choice the correct definition.

Tags

NGSS.MS-PS1-1

Any form of matter that is uniform throughout and has consistent properties

• Atom

• Molecule

• Substance

• Solid

Answer explanation

A substance is defined as any form of matter that is uniform throughout and has consistent properties. Unlike atoms and molecules, which are components of substances, a substance itself represents a uniform material.

All of the following are examples of subatomic particles EXCEPT –

• Neutrons

• Protons

• Electrons

• Neurons

Answer explanation

Neurons are not subatomic particles; they are cells in the nervous system. In contrast, neutrons, protons, and electrons are all fundamental components of atoms, making them subatomic particles.

When two or more atoms bind together, they form a/an–

• Cloud

• Atom

• Molecule

• Solid

Answer explanation

When two or more atoms bind together, they form a molecule. A molecule is the smallest unit of a chemical compound that retains its chemical properties, distinguishing it from other options like cloud, atom, or solid.

Tags

NGSS.MS-PS1-1