Mid-Unit Assessment (Atomic Structure & the Periodic Table)

What is one POSTULATE in "Dalton's Atomic Theory?"

• Chemical reactions can change an atom into a different atom.

• Electrons circle around the nucleus.

• Atoms of the same element have different numbers of protons.

• All matter is made up of atoms.

Think about drawing Bohr models of atoms using circles for orbitals.

Electrons circle around the nucleus in these orbitals.

How many orbitals can fit in the FIRST orbital--the one closest to the nucleus in the center?

• 2

• 3

• 4

• 8

What is the charge on a proton?

• 0

• +1

• -1

What is the charge on a neutron?

• 0

• +1

• -1

What is the charge on an electron?

• 0

• +1

• -1

If there are too many or too few neutrons in an atom, what can happen?

(Think of what you know about radioactive isotopes.)

• The elements can form ions.

• A chemical reaction can occur.

• The protons can fuse with other protons.

• The nucleus can become unstable.

What is TRUE about the atomic NUMBER?

• It equals the number of protons in an element.

• It changes for isotopes of the same element.

• It represents the mass of the nucleus

• It changes for different ions of an element.

A positive ion is called a(n) ___________.

• anion

• cation

A negative ion is called a(n) ________.

• anion

• cation

If a sodium atom (Na) has 4 neutrons, 3 protons, and 2 electrons, which of the following is the correct ION SYMBOL?

• Na

• Na-1

• Na+1

• Na+3