Emma SCI Atom and Atomic Theory

What is the mass of 2.5 mol of Ca, which has a molar mass of 40 g/mol?

• 2.5 g Ca

• 20.0 g Ca

• 40.0 g Ca

• 100.0 g Ca

How many valence electrons does Potassium (K) have?

• 1

• 2

• 3

• 4

Avogadro's number is useful for

• counting atoms

• locating an atom's electrons

• counting large objects

• None of the above

The charge of a stable atom is

• positive

• negative

• neutral

• unbalanced

An iron (Fe) atom has an atomic mass of 56. Its atomic number is 26. How many neutrons does this iron atom have?

• 30

• 56

• 26

• 82

An element's atomic number is equal to its number of

• protons

• neutrons

• valence electrons

• protons and neutrons

An element's mass number is equal to its number of what?

• protons

• neutrons

• protons + neutrons

• electrons

An element's net charge is equal to the difference of the charges of what?

• protons

• neutrons

• protons + neutrons

• electrons

Two different isotopes of an element have a different...

• number of neutrons

• number of protons

• atomic numbers

• number of electrons

What is the mass number of an element that has 19 protons, 19 electrons, and 20 neutrons?

• 19

• 39

• 20

• 58