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frozen [14]
3 years ago
9

How many protons,neutrons and electrons are present in an atom of hafnium,hf,with a mass number of 178?

Chemistry
2 answers:
AleksAgata [21]3 years ago
7 0
178 of each species
178 protons
178 neutrons
And 178 electrons
AlladinOne [14]3 years ago
4 0

Answer:

72 protons

102 neutrons

72 electrons

Explanation:

Hf has an atomic number of 72. By definition, this means that it has 72 protons.

It also has a mass number of 178. The mass number (A) counts all elements with significant mass (protons and neutrons). Then,

A = p⁺ + n⁰

n⁰ = A - p⁺ = 178 - 72 = 102

Hf has 102 neutrons.

Elemental Hafnium is electrically neutral because it has the same amount of  positive charges (protons) and negative charges (electrons). Then, it must have 72 electrons.

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A 10.0-g sample of sodium chloride was placed in 10.0 g of water. If 3.85 g of Cl2 was obtained, what was the percent yield of C
suter [353]

Answer:

63.53% yield

Explanation:

The balanced equation for this reaction is 2NaCl + H2O -> 2NaOH +Cl2

First we must find the limiting reactant

From NaCl we can only produce 6.06 grams of Cl2 in <u>theory</u>

From H20 we can only produce 38.995 grams in theory

so we know NaCl is the limiting

% yield is (Actual/Theoretical) x100 so

(3.85/6.06)x100= 63.53% yield

7 0
3 years ago
Which element has the highest electronegativity and why?
BigorU [14]

Answer:

See below

Explanation:

Hello there!

Electronegativity is the atom's tendency to attract electrons in a chemical bond

There are two trends to electronegativity:

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  • Electronegativity increases from left to right across a period (the further right the group, the greater the electronegativity)

Looking at a period table, Sb, Sn, Te, and I are all in the same period, so we'll need to decide which element has the highest electronegativity based on the group.

  • Sn belongs to group 4A (group 14)
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  • Te belongs to group 6A (group 16)
  • I belongs to group 7A  (group 17)

As I belongs to group 7A, the group that is the farthest right based off of the options given, I has the highest electronegativity

Hope this helps!

8 0
2 years ago
Why is the dipole moment of so2 1.63 d but that of co2 is zero?
borishaifa [10]
SO2<span> molecule </span>have a dipole moment<span> and a </span>CO2<span> molecule doesn't ... </span>Dipole moment<span> of </span>CO2<span> molecule </span>is zero<span>,becoz it is linear molecule,whereas </span>SO2<span> is angular</span>
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3 years ago
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Na

hope this helps :)

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3 years ago
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tigry1 [53]
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3 0
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