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)     1s²2s²2p⁶3s²3p⁶3d⁶ 

(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 (p_x, p_y, p_z) ands must have parallel spin (either all upspin or all downspin, it doesn't matter which).