Lesson 2

Question 1

What are atoms of the same element with different numbers of neutrons called?

Answer 1

Isotopes

Most naturally occurring elements exist as isotopes.

Question 2

What is the mass number of an isotope?

Answer 2

The sum of the number of protons and neutrons in the nucleus

The mass number helps distinguish between different isotopes of the same element.

Question 3

What is the most common isotope of hydrogen?

Answer 3

Protium

Protium has a single proton in its nucleus.

Question 4

What is deuterium?

Answer 4

An isotope of hydrogen with one proton and one neutron

Deuterium is a stable isotope and occurs naturally in small amounts.

Question 5

What is tritium?

Answer 5

An isotope of hydrogen with one proton and two neutrons

Tritium is very rare and is radioactive.

Question 6

What are electron shells?

Answer 6

Energy levels that electrons occupy around the nucleus

Electron shells play a crucial role in determining an atom’s chemical properties.

Question 7

What are the letters used to designate subshells?

Answer 7

s, p, d, and f

Each subshell has a specific capacity for electrons.

Question 8

What does the principal quantum number ‘n’ represent?

Answer 8

The name, size, and energy of the shell

The value of n can range from 1 to ∞.

Question 9

Fill in the blank: The arrangement of electrons in subshells determines the _______.

Answer 9

Chemical properties of an element

Question 10

True or False: All isotopes of hydrogen are stable.

Answer 10

False

Tritium, for example, is radioactive.