Q: Which of the following is the correct formula for calculating the number of neutrons in an atom?

$$\text{Number of neutrons} = \text{Mass number} - \text{Atomic number}$$

Question 1

Which of the following statements best describes an element?

Accepted Answer

A substance that consists of identical atoms and cannot be broken down to simpler substances.

Question 2

Which scientist is credited with arranging the periodic table by increasing atomic number, which is the modern basis for the table?

Accepted Answer

Henry Moseley

Question 3

What is the correct symbol for the element named after the planet Uranus?

Accepted Answer

U

Question 4

Which of the following elements is a metalloid?

Accepted Answer

Boron (B)

Question 5

According to Dalton’s Atomic Theory, which statement is INCORRECT based on modern understanding?

Accepted Answer

Atoms of a particular element have identical properties.

Question 6

Which experiment led to the discovery of the nucleus in the atom?

Accepted Answer

Gold foil experiment

Question 7

How many protons, neutrons, and electrons are in an atom of bromine (Br) with a mass number of 80?

Accepted Answer

$$35$$ protons, $$45$$ neutrons, $$35$$ electrons

Question 8

Which of the following best describes an isotope?

Accepted Answer

Atoms of the same element with different numbers of neutrons.

Question 9

What is the electron arrangement for magnesium (Mg), atomic number 12?

Accepted Answer

$$2, 8, 2$$

Question 10

Which group in the periodic table contains the noble gases?

Accepted Answer

Group 8A

Question 11

Which of the following trends is correct for atomic size as you move down a group in the periodic table?

Accepted Answer

Atomic size increases

Question 12

Which of the following elements is most likely to lose electrons and form positive ions?

Accepted Answer

Sodium (Na)

Question 13

What is the correct Lewis symbol for carbon (C)?

Accepted Answer

C with 4 dots around it

Question 14

Which of the following best explains why ionization energy increases across a period?

Accepted Answer

The number of protons increases, increasing attraction to electrons.

Question 15

Which element is a major element in the human body and is also a nonmetal?

Accepted Answer

Oxygen (O)

Question 16

A photon of ultraviolet light has more energy than a photon of visible light because:

Accepted Answer

Ultraviolet light has a shorter wavelength.

Question 17

Which of the following is the correct formula for calculating the number of neutrons in an atom?

Accepted Answer

$$	ext{Number of neutrons} = 	ext{Mass number} - 	ext{Atomic number}$$

Question 18

Which property increases as you move from left to right across a period in the periodic table?

Accepted Answer

Ionization energy

Question 19

Which of the following best describes the arrangement of electrons in Bohr’s model of the atom?

Accepted Answer

Electrons orbit the nucleus in specific energy levels.

Question 20

A sample of nitrogen contains 99.636% $$^{14}	ext{N} ($$atomic mass = 14.003 amu) and 0.364% $$^{15}	ext{N} ($$atomic mass = 15.000 amu). What is the atomic mass of nitrogen? (Round to 3 decimal places)

Accepted Answer

$$14.007$$ amu

Atoms and Elements: Structure, Properties, and Periodic Trends

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