Docsity
Docsity

Prepare for your exams
Prepare for your exams

Study with the several resources on Docsity


Earn points to download
Earn points to download

Earn points by helping other students or get them with a premium plan


Guidelines and tips
Guidelines and tips

Atomic Structure and Electron Shielding, Study notes of Chemistry

Information on the atomic structure of various elements, including the number of protons, neutrons, and electrons in their atoms, and the concept of shielding and effective nuclear charge. It also includes instructions on how to calculate the energy required to excite an electron in a hydrogen atom using the bohr model.

Typology: Study notes

2021/2022

Uploaded on 09/12/2022

agrata
agrata 🇺🇸

4

(7)

258 documents

1 / 2

Toggle sidebar

This page cannot be seen from the preview

Don't miss anything!

bg1
71
During Class Invention
Shielding
Name(s) with Lab section in Group
______________________
__________________________________________________
1. How many electrons, protons and neutrons in the following atoms?
Atom
Nuclear Charge
#protons
#neutrons
# electrons
H
+1
1
0
1
He
+2
2
2
2
Ne
+10
10
10
10
2. How would we remove an electron from a hydrogen atom? How would we excite an
electron in a hydrogen atom?
By adding enough energy to ionize the atom (remove an electron). To excite an
electron in an atom we need to add an amount of energy that is exactly equal to the
energy separation between two energy level. (See the Bohr Model DCI to calculate
the energy required to excite an electron from n = 1 to n = 4 level.)
3. Write a chemical equation that describes the first ionization energy for
a) a hydrogen atom
energy + H(g) H+(g) + 1e
d) a helium atom
energy + He(g) He+(g) + 1e
e) a neon atom
energy + Ne(g) Ne+(g) + 1e
4. For each of the following atoms what ‘core’ charge are the electrons in the outer shell
attracted by?
a) Hydrogen Z = +1 there are no inner core electrons so the core charge is +1.
b) Lithium Z = +3. The electron configuration for lithium is 1s22s1. There are two inner
core electrons shielding the valence electron from some of the nuclear charge so the
core charge for the valence electron in lithium is +1.
c) Beryllium Z = +4. The electron configuration for beryllium is 1s22s2. There are two
inner core electrons shielding the valence electron from some of the nuclear charge
so the core charge for the valence electron in beryllium is +2.
d) Fluorine Z = +9. The electron configuration for fluorine is 1s22s22p5. There are two
inner core electrons shielding the valence electron from some of the nuclear charge
so the core charge for the valence electron in fluorine is +9.
pf2

Partial preview of the text

Download Atomic Structure and Electron Shielding and more Study notes Chemistry in PDF only on Docsity!

During Class Invention

Shielding

Name(s) with Lab section in Group



  1. How many electrons, protons and neutrons in the following atoms?

Atom Nuclear Charge #protons #neutrons # electrons

H +1 1 0 1

He +2 2 2 2

Ne +10 10 10 10

  1. How would we remove an electron from a hydrogen atom? How would we excite an electron in a hydrogen atom?

By adding enough energy to ionize the atom (remove an electron). To excite an electron in an atom we need to add an amount of energy that is exactly equal to the energy separation between two energy level. (See the Bohr Model DCI to calculate the energy required to excite an electron from n = 1 to n = 4 level.)

  1. Write a chemical equation that describes the first ionization energy for

a) a hydrogen atom energy + H(g) → H+(g) + 1e–

d) a helium atom energy + He(g) → He+(g) + 1e–

e) a neon atom energy + Ne(g) → Ne+(g) + 1e–

  1. For each of the following atoms what ‘core’ charge are the electrons in the outer shell attracted by?

a) Hydrogen Z = +1 there are no inner core electrons so the core charge is +1.

b) Lithium Z = +3. The electron configuration for lithium is 1s^2 2s^1. There are two inner core electrons shielding the valence electron from some of the nuclear charge so the core charge for the valence electron in lithium is +1. c) Beryllium Z = +4. The electron configuration for beryllium is 1s^2 2s^2. There are two inner core electrons shielding the valence electron from some of the nuclear charge so the core charge for the valence electron in beryllium is +2. d) Fluorine Z = +9. The electron configuration for fluorine is 1s^2 2s^2 2p^5. There are two inner core electrons shielding the valence electron from some of the nuclear charge so the core charge for the valence electron in fluorine is +9.

e) sulfur Z = +16. The electron configuration for sulfur is 1s^2 2s^2 2p^6 3s^2 3p^4. There are ten inner core electrons shielding the valence electron from some of the nuclear charge so the core charge for the valence electron in sulfur is +6.

  1. What does the term ‘shield’ mean when describing the attraction experienced by an electron in an outer shell?

Shielding is what the inner core electrons do to part of the nuclear charge experienced by the valence electrons. Consider carbon in the Table in DCI25.1. There are 2 inner core electrons (electrons in the n = 1 level), 4 valence electrons and 6 protons in the nucleus. The 2 inner core electrons are shielding the 4 valence electrons from the nucleus. The result is that each of the valence electrons experience an effective nuclear charge of +4.

  1. Complete the following table

Element

Nuclear Charge (same as the atomic number)

Total # of electrons (same as the atomic number)

of inner

core electrons

of valence

Electrons (Outer most electrons)

Effective Nuclear Charge (Z – IC electrons)

hydrogen +1 1 0 1 + lithium +3 3 2 1 + Beryllium +4 4 2 2 + Boron +5 5 2 3 + Carbon +6 6 2 4 + Nitrogen +7 7 2 5 + Oxygen +8 8 2 6 + Fluorine +9 9 2 7 + Sulfur +16 16 10 6 + Potassium +19 19 18 1 + Bromine +35 35 28 7 +