Understanding Subatomic Particles

What does the atomic number of an element represent?

• The number of protons in the nucleus

• The total number of neutrons in an atom

• The average mass of the element's isotopes

• The number of electrons in the outer shell

How is the periodic table organized?

• By increasing atomic mass

• By decreasing atomic number

• By increasing atomic number

• By alphabetical order of elements

What is the average atomic mass of an element?

• The mass of the most common isotope

• The sum of protons and neutrons

• The weighted average of all isotopes

• The total number of electrons

Which of the following is true about isotopes?

• They are always radioactive

• They have the same atomic mass

• They have different numbers of protons and electrons

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

What distinguishes mass number from average atomic mass?

• Mass number is the same as atomic number

• Average atomic mass is always a whole number

• Mass number is always a whole number

• Mass number includes electrons

How do you calculate the number of neutrons in an atom?

• Add the number of protons to the number of electrons

• Subtract the number of electrons from the atomic number

• Subtract the atomic number from the mass number

• Add the atomic number to the mass number

If an element has an atomic number of 11 and a mass number of 23, how many neutrons does it have?

• 34

• 23

• 12

• 11

What is the atomic number of an element with 29 protons?

• 64

• 42

• 29

• 15

Which element has an atomic number of 20?

• Sodium

• Magnesium

• Potassium

• Calcium

How many neutrons are in an isotope of strontium with a mass number of 89 and 38 protons?

• 27

• 38

• 89

• 51