1. Which element has the following electron configuration? a) [He]2s1 b) [He]2s2

Question

1. Which element has the following electron configuration?
a) [He]2s1
b) [He]2s2 2p3
c) [Ne]3s2 3p3
d) [Ar]4s1 3d10
e) [Ar]4s2 3d10 4p6
f) [Ar]4s1 3d5
2. Write the number of core and valence electrons in Ca and Mg.
3. Identify the element:
a) Contains 10 core electrons and 5 valence electrons.
b) It's (1+) ion contains 18 core electrons and 7 valence electrons.
4. Rearrange the following atoms/ions in decreasing order of radius:
a) Cl, Mg, Ca, Ba
b) Al3+, Mg2+, Ca2+, F1-, O2-
c) Pb, Sn, Si, As
5. Write down the set of isoelectronic ions (4 each) that have the same ion configuration as the noble gas.
a) [Ne] ___, ____, ___, ___
b) [Ar] ___, ___, ___, ___
6. Arrange the second period atoms in increasing order of electron affinity (Li, Be, B, C, N, O, F, Ar)
7. Arrange the second period atoms in increasing order of first ionization energy.
8. Write the condensed electron configuration for the following ions:
a) Zn2+
b) Co2+
c) Mn3+
d) Se2-
e)Ti+
f) Sn2+
9. True or false?
a) Effective nuclear charge decreases going down in a group.
b) Zeff for Ca is smaller than that of Cl.
c) Al3+ is larger than Na+ because Na+ has 2 extra electrons.
d) Effective nuclear charge (Zeff) is the positive charge experienced by the electron from the nucleus and it increases from left to right across the period.
e) Anions are larger than their parent atoms because electrons are added to the valence shell reducing the electron-electron repulsions.
f) The ionization energy of Na2+ is significantly higher than Na+ because it takes more energy to remove the inner-shell electron.
g) Atomic radius tends to decrease from top to bottom of a group because of the increase in the principle quantum number.
h) Br, Ca, and Na are metallic elements because they are on the left side of the periodic table.
I) Ca, Antimony, Si are metalloids that their properties fall between those of metals and those of nonmetals.
10. Rearrange the following compounds in order of increasing acidity: CO2, P2O5, CaO, SO3, SiO2, CO2
11. Consider the elements B, Ca, Cl, O, S.
a) Identify the element that is most-likely to form an ionic bond with magnesium.
b) Identify the element that is most likely to form a covalent bond with nitrogen.
12. See photo.

Explanation / Answer

There are too many questions ......i will try to all....please post separately

1)

a) [He]2s1     = lithium
b) [He]2s2 2p3 = nitrogen
c) [Ne]3s2 3p3 = phosphorous
d) [Ar]4s1 3d10 = potasiun
e) [Ar]4s2 3d10 4p6 = krypton
f) [Ar]4s1 3d5   = chromium

2) 2. Write the number of core and valence electrons in Ca and Mg.

Ca = core    18 electrons   and valence electron = 2

Mg = core    10electrons   and valence electron = 2

3)

Identify the element:
a) Contains 10 core electrons and 5 valence electrons.

atomic number = 15 , so its phosphorous
b) It's (1+) ion contains 18 core electrons and 7 valence electrons.

   total electron in ion = 25

total electron in neutral atom = 25 + 1 = 26 , so its iron

4. Rearrange the following atoms/ions in decreasing order of radius:
a) Cl, Mg, Ca, Ba

ans :    Cl < Mg < Ca< Ba
b) Al3+, Mg2+, Ca2+, F1-, O2-

all are isoelectronic so , ion with higher atomic no is smaller

Al3+ < Mg2+, <, F1-, < O2-

5. Write down the set of isoelectronic ions (4 each) that have the same ion configuration as the noble gas.
a) [Ne] ___, ____, ___, ___ answer = O-2, N-3,F-1, Na+1
b) [Ar] ___, ___, ___, ___ Answer = S-2, P-3,Cl-1, K+1

please post the reamaining separatelty

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