Ions Isotopes and Average Atomic Mass

Atoms of the same element which have a different number of neutrons are called _________________.

• ions

• isotopes

• quarks

• molecules

How many neutrons does C-14 contain? (tap to enlarge the image)

• 6

• 7

• 14

• 8

How many neutrons does an atom of the isotope Neon-22 have? (tap to enlarge the image)

• 12

• 10

• 22

• 20

How many electrons are in an neutral atom with an atomic number of 50?

• 5

• 8

• 50

• 2

which atom has  4 neutrons?

• Li-6
• Li-7
• Li-8
• they have the same # of neutrons

Tags

NGSS.MS-PS1-1

The average atomic mass of an element is the ___.

• average of the mass number and the atomic number for the element

• average of the masses of the isotopes of the element

• total mass of the isotopes of the element

• total number of subatomic particles in the nucleus

How many protons would an atom or ion of sodium have?

(Time to get comfortable using pages 10 and 11 of your Reference Tables to learn names and symbols of the elements, then go to the Periodic Table on p9)

• 23

• 7

• 14

• 11

Answer explanation

The element symbol Na stands for sodium, which is atomic number 11.

That means it has 11 protons.

regardless if we are talking about an atom or an ion of sodium... it will have 11 protons. That is the key characteristic for being called sodium.

What is the shorthand name for the nuclide with 12 protons and 13 neutrons?

• Al-13

• Mn-25

• Mg-12

• Mg-25

• Al-25

Answer explanation

The number of protons determines the element. 12 protons means it must be magnesium, Mg.

Then, the second half of the naming convention is to list the mass number. Mass number (A) = protons + neutrons. Thus 25.

Put them together and you can say Mg-25... magnesium-25

Tags

NGSS.MS-PS1-1

How many neutrons does an atom of Ca-42 have?

• 42

• 20

• 22

• 36

• 27

Answer explanation

Ca-42 is an atom of calcium with mass number 42. That means that # protons + # neutrons = 42.

Every calcium atom has 20 protons because it has atomic number is 20.

42-20 = 22

Be careful when looking up the element symbol for an element name.

Careful not to mix up Ca with Co or Cu

If 19.9% of Boron exists as Boron-10 and 80.1% is Boron-11, what is the average atomic mass of Boron?

• 10.199 amu

• 10.233 amu

• 10.801 amu

• 11.245 amu