Question 1

Which of the following best distinguishes an element from a compound?

Accepted Answer

An element is a substance that cannot be broken down into other substances by chemical reactions, while a compound consists of two or more elements combined in a fixed ratio.

Question 2

A neutral atom of phosphorus has an atomic number of 15 and a mass number of 31. How many neutrons does it have?

Accepted Answer

$$31 - 15 = 16$$ neutrons

Question 3

Which statement correctly compares a neutron and a proton?

Accepted Answer

A neutron has no electrical charge, while a proton has a positive charge.

Question 4

Which of the following best describes the difference between atomic number and mass number?

Accepted Answer

Atomic number is the number of protons in an atom, while mass number is the sum of protons and neutrons.

Question 5

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 6

Which of the following best explains how electron configuration influences the chemical behavior of an atom?

Accepted Answer

The chemical behavior of an atom is largely determined by the number of electrons in its outermost shell (valence electrons).

Question 7

Which of the following is the correct electron configuration for a neutral oxygen atom ($$Z = 8$$)?

Accepted Answer

$$1s^2$$\ $$2s^2$$\ $$2p^4$$

Question 8

Which of the following best describes a nonpolar covalent bond?

Accepted Answer

A bond in which two atoms share electrons equally because they have similar electronegativities.

Question 9

How many electrons are shared in a double covalent bond?

Accepted Answer

4 electrons

Question 10

Which of the following best defines electronegativity?

Accepted Answer

The tendency of an atom to attract electrons toward itself in a chemical bond.

Question 11

Which of the following statements correctly distinguishes between hydrogen bonds, covalent bonds, and ionic bonds?

Accepted Answer

Hydrogen bonds are weak attractions between a hydrogen atom and an electronegative atom, covalent bonds involve sharing of electrons, and ionic bonds involve transfer of electrons.

Question 12

A molecule of methane ($$CH_4) is $$formed when carbon shares electrons with four hydrogen atoms. What type of bond is formed between carbon and hydrogen?

Accepted Answer

Nonpolar covalent bond

Question 13

If sodium ($$Na) $$has an atomic number of 11 and chlorine ($$Cl) $$has an atomic number of 17, what type of bond forms between them in table salt ($$NaCl$$), and why?

Accepted Answer

Ionic bond, because sodium donates an electron to chlorine, resulting in oppositely charged ions that attract each other.

Question 14

Which of the following best explains why water ($$H_2O) is a $$polar molecule?

Accepted Answer

Oxygen is more electronegative than hydrogen, causing unequal sharing of electrons and partial charges on the molecule.

Question 15

A radioactive isotope of carbon, $$^{14}C$$, has 6 protons and 8 neutrons. What is its mass number?

Accepted Answer

$$6 + 8 = 14$$

Question 16

Which of the following scenarios best illustrates the building up principle (Aufbau principle) for electron configuration?

Accepted Answer

Electrons fill the lowest available energy orbitals first before moving to higher energy orbitals.

Question 17

Which of the following best describes the relationship between atomic weight and mass number?

Accepted Answer

Atomic weight is the average mass of all isotopes of an element, while mass number is the total number of protons and neutrons in a specific atom.

Question 18

Which of the following is a real-world example of an ionic compound and the process by which it forms?

Accepted Answer

Table salt ($$NaCl) $$forms when sodium donates an electron to chlorine, resulting in $$Na^+$$ and $$Cl^-$$ ions that are held together by electrostatic attraction.

Question 19

Which of the following best explains why noble gases such as neon ($$Ne) $$are chemically unreactive?

Accepted Answer

Their outermost electron shells are full, making them stable and unlikely to form chemical bonds.

Chapter 2: The Chemical Context of Life – Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards