Chapter 7 Test Review

a substance; only one kind of atom.

• atom

• element

• atomic number

• chemical change

• chemical formula

Answer explanation

An element is a pure substance made of only one kind of atom, distinguishing it from compounds or mixtures. Therefore, the correct answer is 'element'.

the smallest piece of an element that can be recognized as that element.

• atomic number

• atom

• chemistry

• chemical change

• chemical formula

Answer explanation

The smallest piece of an element that retains its properties is called an atom. Other options like atomic number and chemical formula refer to characteristics or representations of elements, not the fundamental unit itself.

Tags

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the study of matter—what it is made of, what its usual characteristics are, how it reacts to other matter.

• chemistry

• chemical change

• chemical formula

• atom

• atomic number

Answer explanation

The study of matter, its composition, characteristics, and reactions is defined as chemistry. This field encompasses all aspects of substances and their interactions, making it the correct choice.

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an atom that has gained or lost electrons.

• ion

• atomic number

• atom

• chemical formula

• chemical change

Answer explanation

An atom that has gained or lost electrons is called an ion. This change in electron number results in a charged particle, distinguishing it from a neutral atom.

the process in which different types of atoms join and form a new substance.

• chemical change

• atom

• chemistry

• atomic number

• chemical formula

Answer explanation

The process described is a chemical change, where different types of atoms combine to create a new substance. This distinguishes it from other terms like atom or chemistry, which do not specifically refer to the formation of new substances.

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based on the number of protons in the nucleus.

• atomic number

• atom

• chemistry

• chemical change

• chemical formula

Answer explanation

The atomic number is defined as the number of protons in the nucleus of an atom. It uniquely identifies an element and determines its position in the periodic table, making it the correct choice for this question.

Tags

NGSS.MS-PS1-1

chemical symbols and numbers abbreviating the name of a compound.

• chemical change

• atom

• atomic number

• chemical formula

• chemistry

Answer explanation

A chemical formula is a representation of a compound using chemical symbols and numbers, indicating the types and quantities of atoms present. This matches the description given in the question.

an ionic compound produced from a reaction between an acid and a base.

• H. salt

• A. atom

• B. atomic number

• D. chemical formula

• C. chemical change

Answer explanation

The correct answer is H. salt, as it is the ionic compound formed when an acid reacts with a base, neutralizing each other and resulting in a salt and water.

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Identify the characteristics as belonging to an acid (A) or a base (B). 13. lemons, vinegar, tomato juice.

• A

• B

Answer explanation

Lemons, vinegar, and tomato juice are all acidic substances, which is why they are classified as acids (A). They contain citric acid or acetic acid, contributing to their sour taste.

Identify the characteristics as belonging to an acid (A) or a base (B). 14. slippery to touch.

• A

• B

Answer explanation

The characteristic 'slippery to touch' is associated with bases. Bases feel slippery due to their ability to react with oils and fats, making them feel smooth, while acids do not have this property.