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2 years ago

Re-order each list in the table below, if necessary, so that the atoms or ions in it are listed in order of decreasing size.

Chemistry

1 answer:

Serjik [45]2 years ago

7 0

Answer: Na, S, Cl

Explanation:

Atomic size decreases as one moves from left to right on the periodic table with elements in the same period. This is as a result of the electrons increasing in the outer circle and thus being drawn to the protons in the nucleus which will lead to the outer shell area decreasing.

Sodium (Na) comes before Sulfur (S) which comes before Chlorine (S) so this is the decreasing order as they are all in the same period.

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Why do the elements in a group all behave similarly

Svetradugi [14.3K]

Answer:

See the explanation below, please.

Explanation:

The elements of the periodic table that belong to the same group (each column) have similar physical and chemical properties. This is because they have the same number of electrons in their last electronic layer.

Example of electronic configuration of elements of GROUP IA:

Hydrogen: 1s ^ 1

Lithium: 1s ^ 2 2s ^ 1

6 0

3 years ago

Which of the following is an example of qualitative observation?Select one of the options below as your answer:. A. Joseph is ob

vekshin1

<h2>Answer : Option C) Joseph is observing the color of the reaction mixture to see whether proteins are present in the given solution.</h2><h3>Explanation :</h3>

An example of qualitative observation is the one where one uses the five senses to identify the changes in the reaction.

Here, when Joseph is studying a reaction mixture he is trying to observe a color change which will confirm that there is proteins present in the reaction mixture or not If there is a color change observed then it will confirm the presence of proteins.

Usually qualitative observations are those which can be easily predicted by using five senses.

5 0

3 years ago

Read 2 more answers

The unit cell for cr2o3 has hexagonal symmetry with lattice parameters a = 0.4961 nm and c = 1.360 nm. If the density of this ma

IRINA_888 [86]

To calculate the packing factor, first calculate the area and volume of unit cell.

Area is calculated as:

$A=6R^{2}\sqrt{3}$

Here, R is radius and is related to a as follows:

$R=\frac{a}{2}$

Putting the value in expression for area,

$A=6(\frac{a}{2})^{2}\sqrt{3}=1.5a^{2}\sqrt{3}$

The value of a is 0.4961 nm

Since, $1 nm=10^{-7}cm$

Thus, $0.4961 nm=4.961\times 10^{-8} cm$

Putting the value,

$Area=1.5(4.961\times 10^{-8}cm)^{2}\sqrt{3}=6.39\times 10^{-15}cm^{2}$

Now, volume can be calculated as follows:

$V=Area\times c$

The value of c is 1.360 nm or $1.360\times 10^{-7} cm$

Putting the value,

$V=(6.39\times 10^{-15}cm^{2})\times (1.360\times 10^{-7} cm)=8.7\times 10^{-22}cm^{3}$

now, number of atom in unit cell can be calculated by using the following formula:

$n=\frac{\rho N_{A}V_{c}}{A}$

Here, A is atomic mass of $Cr_{2}O_{3}$ is 151.99 g/mol.

Putting all the values,

$n=\frac{(5.22 g/cm^{3})(6.023\times 10^{23} mol^{-1})(8.7\times 10^{-22}cm^{3})}{(151.99 g/mol)}\approx 18$

Thus, there will be 18 $Cr_{2}O_{3}$ units in 1 unit cell.

Since, there are 2 Cr atoms and 3 oxygen atoms thus, units of chromium and oxygen will be 2×18=36 and 3×18=54 respectively.

The atomic radii of $Cr^{3+}$ and $O^{2-}$ is 62 pm and 140 pm respectively.

Converting them into cm:

$1 pm=10^{-10}cm$

Thus,

$r_{Cr^{3+}}=6.2\times 10^{-9}cm$

and,

$r_{O^{2-}}=1.4\times 10^{-8}cm$

Volume of sphere will be sum of volume of total number of cations and anions thus,

$V_{S}=V_{Cr^{3+}}+V_{O^{2-}}$

Since, volume of sphere is $V=\frac{4}{3}\pi r^{3}$ ,

$V_{S}=36\left ( \frac{4}{3}\pi (r_{Cr^{3+})^{3}} \right )+54\left ( \frac{4}{3}\pi (r_{O^{2-})^{3}} \right )$

Putting the values,

$V_{S}=36\left ( \frac{4}{3}(3.14) (6.2\times 10^{-9} cm)^{3}} \right )+54\left ( \frac{4}{3}(3.14) (1.4\times 10^{-8} cm)^{3}} \right )=6.6\times 10^{-22}\times 10^{-8}cm^{3}$

The atomic packing factor is ratio of volume of sphere and volume of crystal, thus,

$packing factor=\frac{V_{S}}{V_{C}}=\frac{6.6\times 10^{-22}cm^{3}}{8.7\times 10^{-22}cm^{3}}=0.758$

Thus, atomic packing factor is 0.758.

6 0

3 years ago

Read 2 more answers

Find the molecular mass of.

Margaret [11]

Answer:

sodium oxide Nao
aluminum chloride Al2cl3
sodium sulphate Naso4
<em>magnes</em><em>ium</em><em> </em><em>hydroxide</em><em> </em><em>Mgoh2</em>

3 0

3 years ago

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Help!!!

aleksley [76]

Answer:

Q1) Distillation relies on evaporation to purify water

Explanation:

contaminated water is heated to form steam. inorganic compounds and large non-volatile organic molecules do not evaporate with the water and are left behind. The steam then cools and condenses to form purified water

3 0

3 years ago