3.1 The Atom Review

John Dalton thought that atoms

• contain molecules.

• cannot be broken down further.

• are all composed of carbon.

• have no mass.

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NGSS.MS-PS1-5

Using improved chemistry equipment in the late 1700s, chemists observed that mass is neither created nor destroyed in a chemical reaction. This scientific law is called the law of

• definite proportions.

• gravity.

• conservation of mass.

• multiple proportions.

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NGSS.MS-PS1-5

In an experiment, Alex and Rachel discover that their sample of table salt, also known as sodium chloride, NaCl, consists of 39.34% by mass sodium, Na, and 60.66 % by mass chlorine, Cl. Later, Alex wonders what the percentage of Na might be in the table salt in his saltshaker at home. Rachel tells him, correctly, that it is

• 39.34%

• 60.66%

• 90%

• impossible to tell without analyzing the salt.

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NGSS.MS-PS1-1

The fact that every sample of a particular chemical compound contains the same elements in exactly the same proportions by mass is known as the law of

• conservation of energy.

• conservation of mass.

• multiple proportions.

• definite proportions.

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NGSS.HS-PS1-7

A molecule of carbon monoxide, CO, has one atom of oxygen while a molecule of carbon dioxide, CO₂, has two. In a sample of CO containing 1 g of carbon, 1.33 g of oxygen will combine with the carbon to form the molecule. What is the mass of oxygen in a sample of CO₂ containing 1 g of carbon?

• 1.33 g

• 3.0 g

• 2.66 g

• 0.0 g

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NGSS.MS-PS1-5

If two or more compounds are composed of the same two elements, then the ratio of the masses of the second element that is combined with a certain mass of the first element is always a ratio of small whole numbers. This statement is called the law of

• definite proportions.

• conservation of mass.

• conservation of energy.

• multiple proportions.

In 1808, John Dalton established his atomic theory. Which of the following is not part of Dalton's atomic theory?

• All matter is composed of atoms.

• An atom consists of a nucleus and a cloud of electrons.

• Atoms cannot be subdivided, created, or destroyed.

• In chemical reactions, atoms are combined, separated, or rearranged.

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NGSS.MS-PS1-5

Which of the following statements of Dalton's atomic theory describes the law of conservations of mass?

• All matter is composed of atoms

• Atoms of a given element are identical in size, mass, and other properties.

• Atoms cannot be subdivided, created, or destroyed.

• Atoms of different chemical elements combine in simple whole-number ratios to form chemical compounds.

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NGSS.MS-PS1-5

Which of the following statements of Dalton's atomic theory describes the law of multiple proportions?

• All matter is composed of atoms.

• Atoms of a given element are identical in size, mass, and other properties.

• Atoms cannot be subdivided, created, or destroyed.

• Atoms of different chemical elements combine in simple whole-number ratios to form chemical compounds.

Which is one way that Dalton's atomic theory has been shown to be incorrect?

• Atoms can change identity in chemical reactions.

• Atoms can split into subatomic particles.

• Atoms can be destroyed by chemical reactions.

• Some atoms of a particular element are identical to atoms of other elements.

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