Q: Which of the following is the correct formula to calculate the number of neutrons in an atom?

$$\text{Number of neutrons} = \text{mass number} - \text{atomic number}$$

Q: Which of the following pairs are isotopes of the same element?

$$^{16}_{8}\text{O}$$ and $$^{18}_{8}\text{O}$$

Question 1

Which of the following statements best describes an element?

Accepted Answer

An element is a pure substance that cannot be broken down into simpler substances by chemical means.

Question 2

Which of the following is the correct chemical symbol for gold, and what is its origin?

Accepted Answer

Au, from the Latin word 'aurum'

Question 3

Which of the following elements is a metalloid?

Accepted Answer

Silicon

Question 4

A student is given a sample of an unknown element. It is shiny, conducts electricity well, and is malleable. Based on these properties, to which class does this element most likely belong?

Accepted Answer

Metals

Question 5

Which of the following statements about the periodic table is correct?

Accepted Answer

Elements are arranged in order of increasing atomic number.

Question 6

Which group on the periodic table contains the noble gases?

Accepted Answer

Group 8A

Question 7

According to Dalton's atomic theory, which of the following is true?

Accepted Answer

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

Question 8

Which subatomic particle has a positive charge?

Accepted Answer

Proton

Question 9

Rutherford's gold foil experiment led to which major discovery about atomic structure?

Accepted Answer

Atoms have a small, dense, positively charged nucleus.

Question 10

An atom of aluminum has 13 protons and 14 neutrons. What is its mass number?

Accepted Answer

$$27$$

Question 11

Which of the following correctly describes isotopes?

Accepted Answer

Isotopes have the same number of protons but different numbers of neutrons.

Question 12

A neutral atom of chlorine has an atomic number of $$17$$ and a mass number of $$35. $$How many neutrons does it have?

Accepted Answer

$$18$$

Question 13

Which of the following is the correct formula to calculate the number of neutrons in an atom?

Accepted Answer

$$	ext{Number of neutrons} = 	ext{mass number} - 	ext{atomic number}$$

Question 14

A certain isotope of oxygen is represented as $$^{18}_{8}	ext{O}. $$How many protons, neutrons, and electrons does a neutral atom of this isotope have?

Accepted Answer

8 protons, 10 neutrons, 8 electrons

Question 15

Which of the following pairs are isotopes of the same element?

Accepted Answer

$$^{16}_{8}	ext{O}$$ and $$^{18}_{8}	ext{O}$$

Question 16

Which of the following best explains why metalloids are used in semiconductors?

Accepted Answer

They have properties intermediate between metals and nonmetals, allowing them to conduct electricity under certain conditions.

Question 17

A patient is diagnosed with anemia due to a deficiency of an element essential for health. Which element is most likely deficient?

Accepted Answer

Iron

Question 18

If an atom has 15 protons, 16 neutrons, and 15 electrons, what is its atomic number and mass number?

Accepted Answer

Atomic number $$= 15$$, Mass number $$= 31$$

Question 19

Which of the following statements about atoms is correct?

Accepted Answer

The number of protons in an atom determines its identity as an element.

Question 20

A neutral atom of magnesium has an atomic number of $$12$$ and a mass number of $$24. $$How many electrons does it have?

Accepted Answer

$$12$$

Elements, Atomic Structure, and the Periodic Table: GOB Chemistry Study Notes (Week 2)

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