Chapter 7.1-Matter & Atoms

Which is the smallest piece of an element that still represents that element?

• a quark

• an electron

• an atom

• a molecule

Answer explanation

Feedback: An atom is the smallest piece of an element that still represents that element.

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What is matter?

• anything that you can see, hear or feel

• anything with mass that takes up space

• anything that can be burned

• anything that exists

Answer explanation

Feedback: Matter has mass and takes up space.

Which describes the composition of a substance?

• it is always the same

• it is not always the same

• it contains only one type of element

• it contains more than one type of element

Answer explanation

Feedback: A substance is matter that always has the same composition.

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Which is true of the molecules in any compound?

• they contain at least three atoms

• they contain at least two atoms of the same element

• they contain atoms of at least two different elements

• they contain atoms of at least three different elements

Answer explanation

Feedback: Molecules in compounds contain atoms of at least two different elements.

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Which is the best model for a heterogeneous mixture?

• image A

• image B

• image C

• image D

Answer explanation

The substances in heterogeneous mixtures are not evenly mixed.

What is shown here?

• two different ions

• two different elements

• two different isotopes

• two different compounds

Answer explanation

Feedback: Isotopes of the same element contain different numbers of neutrons.

Tags

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Two atoms of the same element can differ in which of the following?

• the number of protons, neutrons, or electrons

• only in the number of protons or electrons

• only in the number of protons or neutrons

• only in the number of neutrons or electrons

Answer explanation

Feedback: Isotopes contain different numbers of neutrons, and ions contain different numbers of electrons. Atoms with different numbers of protons are atoms of different elements.

What is true of all neutral atoms?

• they have equal numbers of neutrons and electrons

• they have equal numbers of protons and neutrons

• they have equal numbers of protons and electrons

• they have equal numbers of protons, neutrons and electrons

Answer explanation

Feedback: All neutral atoms have equal numbers of protons and electrons.

A calcium ion has 20 neutrons, 20 protons, and 18 electrons. What is the ion's charge?

• 2+

• 1+

• 1-

• 2-

Answer explanation

Feedback: A calcium ion has two more protons than electrons, so it has a charge of 2+.

Why is the area around the nucleus called the electron cloud?

• because it contains a dense cloud of many electrons

• because the electrons are constantly moving

• because scientists do not know how many electrons an atom has

• because electrons are large and diffuse particles

Answer explanation

Feedback: The cloud represents the likelihood that an electron is in a particular place at a particular time.

Tags

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