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3 years ago

1.As you move from left to right across a period,the number of valence electrons

Chemistry

2 answers:

Keith_Richards [23]3 years ago

7 0

<h2>Question 1 </h2>

As you move from left to right across a period, <u>the number of valence electrons increases. </u>

<h2>Further Explanation </h2><h3>Valence electrons </h3>

Valence electrons are the number of outermost electrons in the most outer most energy level in an atom of a given element.
Elements in the same group have the same number of valence electrons for example, group 1 elements have one valence electrons, element in group 2 have two valence electrons and so forth.
The number of valence electrons increases across the period from left to right in the periodic table, with the noble gases having the maximum number of valence electrons.

<h2>Question 2 </h2>

Compared with group 2A elements, group 6A elements<u> have more valence electrons. </u>

<h2>Further Explanation </h2><h3>Group 2A elements </h3>

Group 2A elements are also called alkaline earth metals. They are elements in group 2 of the periodic table. These elements include barium, calcium, magnesium, beryllium, and radium.
Elements in group 2A have two valence electrons which gives them a valence of 2.

<h3>Group 6A elements </h3>

Elements in group 6A of the periodic table are also called Chalcogen. They include, non-metals: oxygen, sulfur and selenium and metals: polonium and tellurium.
Elements in Group 6A contain 6 valence electrons in their outermost energy levels.

<h2>Question 3 </h2>

Fluorine is the most reactive element in group 7A of elements.

<h2>Further Explanation </h2><h3>Reactivity of Non-metals down the group </h3>

The reactivity of non-metals decreases down the group in a periodic table. This is because as you move down the group the number of energy levels increases which reduces the nuclear charge and thus reducing the ease of gaining electrons.

<h3>Group 7A elements </h3>

Group 7A elements are also called halogens. Halogens are non-metals in group 7A in the periodic table.
Group 7A contain seven electrons in their outermost energy level and therefore requires one electron to attain a stable configuration.
Reactivity of halogens like other metals decreases down the group, therefore fluorine is the most reactive in the group with iodine being the least reactive.
This is because fluorine has few energy levels compared to other elements in the group and thus has high nuclear charge which makes it easier for an atom of fluorine to gain electrons.

Keywords: Valence electrons, Reactivity, group 2A, group 6A, group 7A of elements

<h3>Learn more about: </h3>

Valence electrons: brainly.com/question/371590
Group 2A of elements: brainly.com/question/8281417
Group 6A of elements: brainly.com/question/1232609
Group 7A of elements: brainly.com/question/2432040
Reactivity of non-metals: brainly.com/question/7718104

Level: High school

Subject; Chemistry

Topic: Chemical families and the periodic table

Sub-topic: Valence electrons and trends in reactivity

Vitek1552 [10]3 years ago

4 0

<span>1. The number of valence electrons increases as you go from left to right across a period. This is because the number of electrons increases, so another electron will be added to the outer shell.

2. Group 6A elements will have 6 valence elecrons, while Group 2A elements only have 2, therefore Group 6A elements have more valence electrons that Group 2A elements.

3. Fluorine has a smaller atomic size than the other halogens (Cl, Br, I), so its valence electrons are nearer to its nucleus. This means that the attractive forces are stronger, so when another electron (from another atom) draws near the F atom, it is more likely that the electron will be pulled toward the nucleus and react with the F atom</span>.

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A certain liquid X has a normal freezing point of 7.60 °C and a freezing point depression constant K= 6.90 °C-kg-mol. Calculate

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<u>Answer:</u> The freezing point of solution is -5.11°C

<u>Explanation:</u>

Vant hoff factor for ionic solute is the number of ions that are present in a solution. The equation for the ionization of sodium chloride follows:

$NaCl(aq.)\rightarrow Na^{+}(aq.)+Cl^-(aq.)$

The total number of ions present in the solution are 2.

To calculate the molality of solution, we use the equation:

$Molality=\frac{m_{solute}\times 1000}{M_{solute}\times W_{solvent}\text{ in grams}}$

Where,

$m_{solute}$ = Given mass of solute (NaCl) = 7.57 g

$M_{solute}$ = Molar mass of solute (NaCl) = 58.44 g/mol

$W_{solvent}$ = Mass of solvent (liquid X) = 350.0 g

Putting values in above equation, we get:

$\text{Molality of }NaCl=\frac{7.57\times 1000}{58.44\times 350.0}\\\\\text{Molality of }NaCl=0.370m$

To calculate the depression in freezing point, we use the equation:

$\Delta T=iK_fm$

where,

i = Vant hoff factor = 2

$K_f$ = molal freezing point depression constant = 6.90°C/m

m = molality of solution = 0.370 m

Putting values in above equation, we get:

$\Delta T=2\times 6.90^oC/m.g\times 0.370m\\\\\Delta T=5.11^oC$

Depression in freezing point is defined as the difference in the freezing point of water and freezing point of solution.

$\Delta T=\text{freezing point of water}-\text{freezing point of solution}$

$\Delta T$ = 5.11 °C

Freezing point of water = 0°C

Freezing point of solution = ?

Putting values in above equation, we get:

$5.106^oC=0^oC-\text{Freezing point of solution}\\\\\text{Freezing point of solution}=-5.11^oC$

Hence, the freezing point of solution is -5.11°C

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