1) A certain element consists of two stable isotopes. The first has a mass of 68
ID: 949590 • Letter: 1
Question
1) A certain element consists of two stable isotopes.
The first has a mass of 68.9 amu and a percent natural abundance of 60.4 %.
The second has a mass of 70.9 amu and a percent natural abundance of 39.6 %.
What is the atomic weight of the element?_________ amu
2)What is the name of the element that is in group 5B and period 4?
What is the name of the element that is in group 8A and period 5?
What is the name of the element that is in group 2B and period 4?
What is the name of the element that is in group 2A and period 2?
3)The element barium is in group _____ and period_______ .
The element tellurium is in group -___________ and period __________
The element chromium is in group________ and period_________
5)The condensed formula for propanoic acid is CH3CH2COOH.
Write the molecular formula for propanoic acid? Enter the elements in the order CHO.
6)Complete the following table:
Fe2+
O2-
Ni2+
F-
Co3+
I-
.
Al3+
NO3-
Ca2+
CH3COO-
Mg2+
CN-
Cation Formula Anion Formula Compound FormulaFe2+
O2-
Ni2+
F-
Co3+
I-
Explanation / Answer
1)
atomic weight = (68.9 x 60.4 ) + ( 70.9 x 39.6) / 100
atomic weight = 69.692
so
the atomic weight is 69.692 amu
2)
group 5 B , period 4 ---> vanadium
group 8A , period 5 --> Xenon
group 2B , period 4 ---> Zinc
group 2A , period 2 ---> Beryllium
3)
barium --> group 2A , period 6
tellurium ---> group 6A , period 5
chromium ---> group 6B , period 4
4)
C3H7NO
5) C3H602
6)
a) FeO
b) NiF2
c) CoI3
d) Al(N03)3
e) Ca(CH3COO)2
f) Mg(CN)2
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