How many protons, electrons, and neutrons? ANSWEN

Chemistry

1 answer:

Step2247 [10]2 years ago

5 0

Answer:

maybe 20 butvam not sure ooo

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ohaa [14]

Answer:Switch off lighting in refrigeration areas when not in use?

Explanation:

7 0

3 years ago

In an experiment, 34.8243g of copper (II) nitrate hydrate, Cu(NO3)2•zH2O was heated to a constant mass of 27.0351g. Calculate th

Leto [7]

Answer:

1) The mass of water lost = 7.7892 grams

2) Z = 3: Cu(NO3)2*3H2O

Explanation:

Step 1: Data given

Mass of copper (II) nitrate hydrate, Cu(NO3)2•zH2O = 34.8243 grams

Mass of substance after heating = 27.0351 grams

Molar mass of Cu(NO3)2 = 187.56 g/mol

Molar mass of H2O = 18.02 g/mol

Step 2: Calculate mass of water

The mass of water is the mass lost after heating.

Mass water = 34.8243 - 27.0351 = 7.7892 grams of water

Step 3: Calculate moles of Cu(NO3)2

Moles Cu(NO3)2 = Mass Cu(NO3)2 / Molar mass Cu(NO3)2

Moles Cu(NO3)2 = 27.0351 grams / 187.56 g/mol

Moles Cu(NO3)2 = 0.144 moles

Step 4: Calculate moles of H2O

Moles H2O = 7.7892 grams / 18.02 g/mol

Moles H2O = 0.432 moles

Step 5: Calculate Z

z = moles H2O / moles Cu(NO3)2

Z = 0.432/0.144

Z = 3

This means we have 3 water molecules in the formula. This makes the formula ofthe hydrate: Cu(NO3)2*3H2O

5 0

3 years ago

9. In a period, do the number of shielding electrons change? Why do you think

Setler79 [48]

Answer:

The nuclear charge increases, but the number of inner shielding electrons stays the same.

Explanation:

Their shielding does not change, so the effective nuclear charge — the charge felt by a valence electron — increases.

The valence electrons are pulled closer to the nucleus, decreasing the atomic radius.

For example, consider the elements of Period 3.

$\begin{array}{ccccc}& & \textbf{Number of} & \textbf{Inner} & \textbf{Valence}\\\textbf{At. No.} & \textbf{Symbol} & \textbf{Protons} & \textbf{Electrons} & \textbf{Electrons}\\11& \text{Na} & 11 & 10 & 1\\12& \text{Mg} &12 & 10 & 2\\13& \text{Al} & 13 & 10 & 3 \\14& \text{Si} & 14 & 10 & 4 \\15& \text{P} & 15 & 10 & 5\\16& \text{S} & 16 & 10 & 6\\17& \text{Cl} & 17 & 10 & 7\\18& \text{Ar} & 18 & 10 & 8 \\\end{array}$