$$ (0.60 \times 10) + (0.40 \times 12) = 6 + 4.8 = 10.8 \ \text{amu} $$

$$ (0.6011 \times 68.9256) + (0.3989 \times 70.9247) = 69.72 \ \text{amu} $$

Question 1

Which statement best describes the main insight from Rutherford's gold foil experiment?

Accepted Answer

Most of the atom's mass and all of its positive charge are concentrated in a small nucleus.

Question 2

A neutral atom of sodium (Na) has an atomic number of 11. How many protons and electrons does it contain?

Accepted Answer

11 protons and 11 electrons

Question 3

Which of the following elements is a metalloid and is widely used in the electronics industry due to its semiconducting properties?

Accepted Answer

Silicon

Question 4

Which of the following best explains why chlorine-35 and chlorine-37 are considered isotopes?

Accepted Answer

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

Question 5

Calculate the atomic mass of an element with two isotopes: 60% with mass 10 amu and 40% with mass 12 amu.

Accepted Answer

$$ (0.60 	imes 10) + (0.40 	imes 12) = 6 + 4.8 = 10.8 \ 	ext{amu} $$

Question 6

Which property is NOT typical of metals?

Accepted Answer

Tends to gain electrons in reactions

Question 7

A fluorine atom gains one electron to form an ion. What is the charge of the resulting ion?

Accepted Answer

$$ 1- $$

Question 8

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

Accepted Answer

Elements in the same group have similar chemical properties.

Question 9

A magnesium ion has 12 protons and 10 electrons. What is its charge?

Accepted Answer

$$ 2+ $$

Question 10

Which experiment provided evidence that atoms are mostly empty space?

Accepted Answer

Rutherford’s gold foil experiment

Question 11

Which of the following ions is isoelectronic with neon (Ne)?

Accepted Answer

$$ 	ext{Na}^+ $$

Question 12

What is the mass number of an isotope of carbon with 6 protons and 8 neutrons?

Accepted Answer

$$ 14 $$

Question 13

Which group in the periodic table contains elements that are all gases at room temperature and are chemically inert?

Accepted Answer

Noble gases

Question 14

A sample of gallium contains 60.11% Ga-69 (68.9256 amu) and 39.89% Ga-71 (70.9247 amu). What is the atomic mass of gallium?

Accepted Answer

$$ (0.6011 	imes 68.9256) + (0.3989 	imes 70.9247) = 69.72 \ 	ext{amu} $$

Question 15

Which of the following best describes a cation?

Accepted Answer

An atom that has lost electrons

Question 16

Which element is defined by having 17 protons in its nucleus?

Accepted Answer

Chlorine

Question 17

Which of the following is a real-world application of radioactive isotopes?

Accepted Answer

Diagnosing diseases using technetium-99

Question 18

Which of the following statements about isotopes is correct?

Accepted Answer

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

Question 19

Which of the following best explains why matter is usually electrically neutral?

Accepted Answer

Atoms contain equal numbers of protons and electrons.

Atoms and Elements: Foundations of Matter (Chapter 4 Study Guide)

Study Guide - Practice Questions