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2 years ago

How does atomic radius change from left to right across a period in the periodic table?

2 answers:

8 0

Atomic radius decrease across the period from left to right because in moving from left to right the nuclear charge increase but the number of electrons remains the same... this unusual disturbances make electrons come closer to the nucleus due to the reason that more protons are present in nucleus of atom as compared to the no of electrons . So attraction occurs between two and thus causes the atomic radius to decrease as going from left to right

Ostrovityanka [42]2 years ago

3 0

Answer: decrease

Explanation:

Atomic radii is the measure of the size of its atoms, usually the mean distance from the centre of the nucleus to the boundary of the surrounding shells of electrons.

The elements in the periodic table are arranged in order of increasing atomic numbers. The horizontal rows are called as periods and vertical columns are called as groups.

The size of an atom decreases as we move across the period because the electrons get added to the same shell and the nuclear charge keeps on increasing. Thus the electrons get more tightly held by the nucleus.

As, the valence electrons come near to the nucleus due to the increased attraction between the nucleus and the shared pair of electrons.

Thus atomic radius decrease from left to right across a period in the periodic table.

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Which body in our solar system has magnetic pole reversals?

sesenic [268]

the correct answer would be the sun

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2 years ago

An excess of sodium carbonate, Na, CO3, in solution is added to a solution containing 17.87 g CaCl2. After performing the

Brrunno [24]

Answer:

Approximately $81.84\%$ .

Explanation:

Balanced equation for this reaction:

${\rm Na_{2}CO_{3}}\, (aq) + {\rm CaCl_{2}} \, (aq) \to 2\; {\rm NaCl}\, (aq) + {\rm CaCO_{3}}\, (s)$ .

Look up the relative atomic mass of elements in the limiting reactant, $\rm CaCl_{2}$ , as well as those in the product of interest, $\rm CaCO_{3}$ :

$\rm Ca$ : $40.078$ .
$\rm Cl$ : $35.45$ .
$\rm C$ : $12.011$ .
$\rm O$ : $15.999$ .

Calculate the formula mass for both the limiting reactant and the product of interest:

$\begin{aligned}& M({\rm CaCl_{2}}) \\ &= (40.078 + 2 \times 35.45)\; {\rm g \cdot mol^{-1}} \\ &= 110.978\; \rm g \cdot mol^{-1}\end{aligned}$ .

$\begin{aligned}& M({\rm CaCO_{3}}) \\ &= (40.078 + 12.011 + 3 \times 15.999)\; {\rm g \cdot mol^{-1}} \\ &= 100.086\; \rm g \cdot mol^{-1}\end{aligned}$ .

Calculate the quantity of the limiting reactant ( $\rm CaCl_{2}$ ) available to this reaction:

$\begin{aligned}n({\rm CaCl_{2}) &= \frac{m({\rm {CaCl_{2}})}}{M({\rm CaCl_{2}})} \\ &= \frac{17.87\; \rm g}{110.978\; \rm g \cdot mol^{-1}} \\ &\approx 0.161023\; \rm mol \end{aligned}$ .

Refer to the balanced equation for this reaction. The coefficients of the limiting reactant ( $\rm CaCl_{2}$ ) and the product ( ${\rm CaCO_{3}}$ ) are both $1$ . Thus:

$\displaystyle \frac{n({\rm CaCO_{3}})}{n({\rm CaCl_{2}})} = 1$ .

In other words, for every $1\; \rm mol$ of $\rm CaCl_{2}$ formula units that are consumed, $1\; \rm mol\!$ of $\rm CaCO_{3}$ formula units would (in theory) be produced. Thus, calculate the theoretical yield of $\rm CaCO_{3}\!$ in this experiment:

$\begin{aligned} & n(\text{${\rm CaCO_{3}}$, theoretical}) \\ =\; & n({\rm CaCl_{2}}) \cdot \frac{n({\rm CaCO_{3}})}{n({\rm CaCl_{2}})} \\ \approx \; & 0.161023\; {\rm mol} \times 1 \\ =\; & 0.161023\; \rm mol\end{aligned}$ .

Calculate the theoretical yield of this experiment in terms of the mass of $\rm CaCO_{3}$ expected to be produced:

$\begin{aligned} & m(\text{${\rm CaCO_{3}}$, theoretical}) \\ = \; & n(\text{${\rm CaCO_{3}}$, theoretical}) \cdot M(({\rm CaCO_{3}}) \\ \approx \; & 0.161023\; {\rm mol} \times 100.086\; {\rm g \cdot mol^{-1}} \\ \approx \; & 16.1161\; \rm g \end{aligned}$ .

Given that the actual yield in this question (in terms of the mass of $\rm CaCO_{3}$ ) is $13.19\; \rm g$ , calculate the percentage yield of this experiment:

$\begin{aligned} & \text{percentage yield} \\ =\; & \frac{\text{actual yield}}{\text{theoretical yield}} \times 100\% \\ \approx \; & \frac{13.19\; {\rm g}}{16.1161\; {\rm g}} \times 100\% \\ \approx \; & 81.84\%\end{aligned}$ .

6 0

2 years ago

What is the difference between a quantity and a unit?

Irina-Kira [14]

$Question$

What is the difference between a quantity and a unit?

Answer:

Physical quantities are a characteristic or property of an object that can be measured or calculated from other measurements. Units are standards for expressing and comparing the measurement of physical quantities. All units can be expressed as combinations of four fundamental units.

Hope this helps!!!

$xXxAnimexXx$

4 0

2 years ago

David found that water can be created in a lab by burning hydrogen gas in air. He concluded that water is not a compound because

Virty [35]

Hi~~

H2O, commonly known as water, is definitely a compound.

David's conclusion is wrong because the hydrogen gas combined with oxygen from the air to form dihydrogen monoxide, also known as water.

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3 years ago

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vampirchik [111]

Answer:

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Similarly, a head teacher from a primary school in the UK recently stated that evolution is a theory rather than a fact. This is despite the fact that children in the UK start learning about evolution in Year 6 (ten to 11-year-olds), and have further lessons throughout high school. While the theory of evolution is well accepted in the UK compared with the rest of the world, a survey in 2005 indicated that more than 20% of the country’s population was not sure about it, or did not accept it.

Explanation:

6 0

2 years ago

Read 2 more answers