Recap Questions

# Question 1

Protons, neutrons and electrons....what are their charges and relative masses?

A: Electrical charges:

Proton is +1, neutron is zero charge and the electron is -1.

Relative masses:

Although they are incredibly tiny, the relative mass of a proton is 1, the neutron is also 1 and the mass of an electron is around 1/2000.

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# Question 2

Q: How are the electrons arranged, in terms of 1s, 2p etc, in the following atoms and ions?

N      (atomic number = 7)

Na    (atomic number = 11)

Ca    (atomic number = 20)

Fe     (atomic number = 26)

Cu    (atomic number = 29)

Fe2+  (atomic number = 26)

Also comment on any special features of the arrangement in N.

A: How are the electrons arranged, in terms of 1s, 2p etc, in the following atoms and ions?

N      (atomic number = 7)     1s22s22p3

Na    (atomic number = 11)   1s22s22p63s1

Ca    (atomic number = 20)    1s22s22p63s23p64s2

Fe     (atomic number = 26)    1s22s22p63s23p64s23d6

Cu    (atomic number = 29)     1s22s22p63s23p64s13d10

but 1s22s22p63s23p64s23d9 would be allowed.

Fe2+  (atomic number = 26)     1s22s22p63s23p63d

(Two less electrons because of the 2+ charge. The order of filling goes back to the main shell numerical order and so the 4s electrrons are the highest energy ones and, consequently, they are the ones to leave.)

Also comment on any special features of the arrangement in N.

The three electrons in the 2p orbitals have to be in three different p orbitals (px, py, pz) ands must have parallel spin (either all upspin or all downspin, it doesn't matter which).