Chapter 4 lesson 2: Distinguishing Among atoms

Question 1

What makes one element different from another?

Answer 1

Elements are different because they contain different numbers of protons.

Question 2

atomic number

Answer 2

the number of protons in the nucleus of an atom of that element.

Question 3

mass number

Answer 3

The total number of protons and neutrons in an atom

Question 4

The rule of finding neutrons:

Answer 4

Number of neutrons = mass number – atomic number

Question 5

How do isotopes of an element differ?

Answer 5

Because isotopes of an element have different numbers of neutrons, they also have different mass numbers.

Question 6

Isotopes

Answer 6

atoms that have the same number of protons but different numbers of neutrons.

Question 7

atomic mass unit (amu)

Answer 7

defined as one-twelfth of the mass of a carbon-12 atom.

Question 8

atomic mass

Answer 8

weighted average mass of the atoms in a naturally occurring sample of the element.

Question 9

How do you calculate the atomic mass of an element?

Answer 9

To calculate the atomic mass of an element, multiply the mass of each isotope by its natural abundance, expressed as a decimal, and then add the products.

resulting in the weighted average mass of the atoms of the element as they occur in nature