$$\text{Ion charge} = 17 - 18 = -1$$

$$\text{Atomic mass} = (0.7577 \times 34.97) + (0.2423 \times 36.97) = 35.45\ \text{amu}$$

$$\displaystyle \frac{31}{15}\text{P}$$

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 magnesium has an atomic number of 12 and a mass number of 24. How many protons, neutrons, and electrons does it contain?

Accepted Answer

12 protons, 12 neutrons, 12 electrons

Question 3

Which property is NOT typical of metals?

Accepted Answer

Tends to gain electrons in chemical reactions

Question 4

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 5

What is the charge on an ion with 17 protons and 18 electrons?

Accepted Answer

$$	ext{Ion charge} = 17 - 18 = -1$$

Question 6

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

Accepted Answer

Noble gases (Group 8A)

Question 7

A sample of chlorine contains 75.77% chlorine-35 (mass 34.97 amu) and 24.23% chlorine-37 (mass 36.97 amu). What is the atomic mass of chlorine?

Accepted Answer

$$	ext{Atomic mass} = (0.7577 	imes 34.97) + (0.2423 	imes 36.97) = 35.45\ 	ext{amu}$$

Question 8

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 9

Which scientist is credited with the first widely accepted atomic theory based on experimental evidence?

Accepted Answer

John Dalton

Question 10

A sodium atom (Na) loses one electron to form an ion. What is the symbol and charge of this ion?

Accepted Answer

$$	ext{Na}^+$$

Question 11

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

Accepted Answer

Matter contains equal numbers of protons and electrons, so their charges cancel.

Question 12

Which element is defined by having 6 protons in its nucleus?

Accepted Answer

Carbon

Question 13

Which of the following is a correct isotope symbol for an atom with 15 protons and 16 neutrons?

Accepted Answer

$$\displaystyle \frac{31}{15}	ext{P}$$

Question 14

Which of the following elements is most likely to form a $$2+$$ ion?

Accepted Answer

Magnesium

Question 15

Which property is shared by all noble gases?

Accepted Answer

They are chemically inert and do not readily form compounds.

Question 16

Which of the following best describes the periodic law as proposed by Mendeleev?

Accepted Answer

When elements are arranged in order of increasing relative mass, certain sets of properties recur periodically.

Question 17

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

Accepted Answer

$$	ext{F}^-$$

Question 18

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

Accepted Answer

Technetium-99 is used in medical imaging to diagnose disease.

Question 19

Which of the following statements about the distribution of mass in an atom is correct?

Accepted Answer

Most of the atom's mass is concentrated in the nucleus.

Question 20

Calculate the number of neutrons in an isotope of uranium-238 ($$^{238}_{92}	ext{U}).$$

Accepted Answer

$$238 - 92 = 146$$ neutrons

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

Study Guide - Practice Questions