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Juliette [100K]
3 years ago
13

Identify the number of valence electrons in each atom: a. Calcium b. Carbon c. Sulfur

Chemistry
2 answers:
RoseWind [281]3 years ago
6 0

Answer:

-Sulfur is a chemical element with the symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formula S₈. Elemental sulfur is a bright yellow, crystalline solid at room temperature.

(Atomic number: 16

Electron configuration: [Ne] 3s²3p⁴

Electrons per shell: 2,8,6

Electronegativity: 2.58)

-Calcium is the 20th element, with 20 protons. Since a stable atom has a net charge of 0, we must have 20 electrons.

-Carbon is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds. It belongs to group 14 of the periodic table. Carbon makes up only about 0.025 percent of Earth's crust.

(Symbol: C

Atomic mass: 12.0107 u

Atomic number: 6

Electrons per shell: 2, 4

Electron configuration: [He] 2s22p2

Electronegativity: 2.55)

Oliga [24]3 years ago
4 0
Look at periodic table and their group number
Calcium - 2
Carbon - 4
Sulfur- 6
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When 21.45 g of KNO3 was dissolved in water in a calorimeter, the temperature fell from 25.00°C to 14.14 °C. If the heat capacit
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25.9 kJ/mol. (3 sig. fig. as in the heat capacity.)

<h3>Explanation</h3>

The process:

\text{KNO}_3\;(s) \to \text{KNO}_3\;(aq).

How many moles of this process?

Relative atomic mass from a modern periodic table:

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Molar mass of \text{KNO}_3:

M(\text{KNO}_3) = 39.098 + 14.007 + 3\times 15.999 = 101.102\;\text{g}\cdot\text{mol}^{-1}.

Number of moles of the process = Number of moles of \text{KNO}_3 dissolved:

\displaystyle n = \frac{m}{M} = \frac{21.45}{101.102} = 0.212162\;\text{mol}.

What's the enthalpy change of this process?

Q = C\cdot \Delta T = 0.505 \times (25.00 - 14.14) = 5.4843\;\text{kJ} for 0.212162\;\text{mol}. By convention, the enthalpy change \Delta H measures the energy change for each mole of a process.

\displaystyle \Delta H = \frac{Q}{n} = \frac{5.4843\text{kJ}}{0.212162\;\text{mol}} = 25.8\;\text{kJ}\cdot\text{mol}^{-1}.

The heat capacity is the least accurate number in these calculation. It comes with three significant figures. As a result, round the final result to three significant figures. However, make sure you keep at least one additional figure to minimize the risk of rounding errors during the calculation.

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What happens when a solid is dissolved in a liquid
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the solid particles take up the intermolecular spaces in the liquid.

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The modern periodic table has groups.
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Arte-miy333 [17]

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2 years ago
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4 0
3 years ago
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