Average Atomic Mass and Periodic Table

An element has two naturally occurring isotopes. One is 10.013 amu and is 19.9% abundant. The other is 11.01 amu and is 80.1% abundant. What is the average atomic mass? What element is it?

• 9.012, Beryllium

• 6.941, Lithium

• 12.011, Carbon

• 10.812, Boron

Naturally occurring chlorine that is put in pools is 75.53 percent 35Cl (mass = 34.969 amu) and 24.47 percent 37Cl (mass = 36.966 amu). Calculate the average atomic mass.

• 35.46 amu

• 35.00 amu

• 37.00 amu

• 17.00 amu

Tags

NGSS.MS-PS1-1

Magnesium has three naturally occurring isotopes. 78.70% of Magnesium atoms exist as Magnesium-24, 10.03% exist as Magnesium-25 and 11.17% exist as Magnesium-26. What is the average atomic mass of Magnesium?

• 14 amu

• 24 amu

• 35 amu

• Cannot be determined based on information given

Tags

NGSS.MS-PS1-1

_____________ are atoms that have the same atomic numbers but differing mass numbers.

• ions

• isotopes

• elements

• compound

Isotopes are elements that have the same number of ____________ but different amounts of ______________.

• same electrons but different protons

• same neutrons but different electrons

• same protons but different electrons

• same protons but different neutrons

Tags

NGSS.MS-PS1-1

Which family have the MOST reactive metals?

• Halogens

• Noble gases

• Alkali metals

• Transition metals

Tags

NGSS.HS-PS1-1

NGSS.HS-PS1-2

Which family have the MOST reactive NON-metals?

• Halogens

• Noble gases

• Alkali metals

• Transition metals

Which family have the little to no reactivity and a full valence shell?

• Halogens

• Noble gases

• Alkali metals

• Transition metals

Which family have variable valence electrons?

• Halogens

• Noble gases

• Alkali metals

• Transition metals

Tags

NGSS.HS-PS1-1

What are more common on the periodic table

• metals

• nonmetals

• metalloids

• radioactive elements