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3 years ago

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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Determine the oxidation states of the elements in the compounds listed. None of the oxygen-containing compounds are peroxides or

Ahat [919]

Answer :

Oxidation number or oxidation state : It represent the number of electrons lost or gained by the atoms of an element in a compound.

Oxidation numbers are generally written with the sign (+) and (-) first and then the magnitude.

Rules for Oxidation Numbers are :

The oxidation number of a free element is always zero.
The oxidation number of a monatomic ion equals the charge of the ion.
The oxidation number of Hydrogen (H) is +1, but it is -1 in when combined with less electronegative elements.
The oxidation number of oxygen (O) in compounds is usually -2.
The oxidation number of a Group 17 element in a binary compound is -1.
The sum of the oxidation numbers of all of the atoms in a neutral compound is zero.
The sum of the oxidation numbers in a polyatomic ion is equal to the charge of the ion.

Now we have to determine the oxidation state of the elements in the compound.

(a) $H_2SO_4$

Let the oxidation state of 'S' be, 'x'

$2(+1)+x+4(-2)=0\\\\x=+6$

Hence, the oxidation state of 'S' is, (+6)

(b) $Ca(OH)_2$

Let the oxidation state of 'Ca' be, 'x'

$x+2(-2+1)=0\\\\x=+2$

Hence, the oxidation state of 'Ca' is, (+2)

(c) $BrOH$

Let the oxidation state of 'Br' be, 'x'

$x+(-2)+1=0\\\\x=+1$

Hence, the oxidation state of 'Br' is, (+1)

(d) $ClNO_2$

Let the oxidation state of 'N' be, 'x'

$-1+x+2(-2)=0\\\\x=+5$

Hence, the oxidation state of 'N' is, (+5)

(e) $TiCl_4$

Let the oxidation state of 'Ti' be, 'x'

$x+4(-1)=0\\\\x=+4$

Hence, the oxidation state of 'Ti' is, (+4)

(f) $NaH$

Let the oxidation state of 'Na' be, 'x'

$x+(-1)=0\\\\x=+1$

Hence, the oxidation state of 'Na' is, (+1)

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3 years ago

1,4-Pentadiene has a AHhydro = -254 kJ/mol while trans-1,3-pentadiene has a AHhydra = -226 kJ/mol. Explain this difference in he

julsineya [31]

Answer:

trans-1,3-pentadiene is more stable than 1,4-pentadiene due to presence of a conjugated double bond.

Explanation:

Here, $\Delta H_{hydro}=H(hydrogenated pdt.)-H(diene)$

H(hydrogenated pdt.) is same for both 1,4-pentadiene and 1,3-pentadiene as they both produce pentane after hydrogenation

H(diene) depends on stability of diene.

More stable a diene, lesser will be it's H(diene) value (more neagtive).

trans-1,3-pentadiene is more stable than 1,4-pentadiene due to presence of a conjugated double bond.

Hence, $\Delta H_{hydro}$ is higher (less negative) for trans-1,3-pentadiene

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Describe how you would use the information depicted in the potential energy diagram below to determine the enthalphy change of t

Oliga [24]

When the formation of a substance is negative, it means that it releases heat to the surroundings. When it releases heat to the surroundings, the reaction is exothermic. When it absorbs heat from the surroundings, the reaction is endothermic.

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Dilute hydrochloric acid+zinc metal

max2010maxim [7]

Explanation:

2HCl+2Zn----> 2ZnCl+H2

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