Understanding the Periodic Table

What is the primary basis for organizing elements in the periodic table?

• Alphabetical order

• Atomic mass

• Atomic number

• Date of discovery

What does the atomic mass of an element represent?

• The number of electrons in the outer shell

• A weighted average of the mass numbers of its isotopes

• The total number of protons and neutrons

• The number of protons in the nucleus

How do you determine the mass number of an element's most common isotope?

• By adding the atomic number and atomic mass

• By rounding the atomic mass to the nearest whole number

• By subtracting the atomic number from the atomic mass

• By dividing the atomic mass by the atomic number

If helium has an atomic mass of 4.003, what is its mass number?

• 3

• 4

• 5

• 6

How many neutrons does the most common isotope of oxygen have?

• 6

• 9

• 8

• 7