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3 years ago

Elements listed in vertical columns of the periodic table:

Chemistry

2 answers:

True [87]3 years ago

6 0

Answer: Option (a) is the correct answer.

Explanation:

It is known that chemical properties of an atom depends on the number of electrons in its outermost shell, that is, valence shell.

For example, Na has 1 electrons in its valence shell and K also has 1 valence electron as both Na and K belongs to the same group.

Therefore, vertical columns in the periodic table represent groups and horizontal lines represent period.

Thus, we can conclude that elements listed in vertical columns of the periodic table have similar chemical properties.

marysya [2.9K]3 years ago

3 0

Vertical columns are called groups, or families.

They share similar chemical properties.

Answer: have similar chemical properties

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How should students prepare to use chemicals in the lab? Select one or more: Sort the lab chemicals in alphabetical order for qu

maksim [4K]

Answer:

Sort the lab chemicals in alphabetical order for quick access.

Become familiar with the chemicals to be used, including exposure or spill hazards.

Locate the spill kits and understand how they are used.

Explanation:

There are many chemicals in a laboratory hence they should be sorted out and arranged in alphabetical order so that theory can easily be identified and located whenever they are required.

The properties of each chemical should be known especially hazards connected to exposure or spill of the chemicals.

The students should also familiarize themselves with the contents of spill kits and how they are used.

7 0

3 years ago

dentify the oxidation state of Cl in Cl 2 O 7 . +2 Identify the oxidation state of Cl in AlCl − 4 . +1 Identify the oxidation st

konstantin123 [22]

Answer:

1. +7

2. -1

3. +3

4. +5

Explanation:

1. Identify the oxidation state of Cl in Cl₂O₇ .

Cl₂O₇ is a neutral compound.

In a neutral compound the oxidation states add up 0.

The oxidation state of oxygen in all the binary compounds, except the peroxides (where two oxygen atoms are bonded together and with other elements) is -2.

Since there are 7 atoms of O, the total oxidation number from it is (-2) × 7 = -14.

Then, the oxidation number from the Cl atoms must add up +14 (because the compound is neutral).

Since there are two atoms of Cl each one must contribute with +14/2 = +7 to the oxidation number.

That is the oxidation state of Cl in the compound. The answer is +7.

2 Identify the oxidation state of Cl in AlCl ₄⁻ (the formula was corrected)

The most common oxidation state of Al is +3.

Since the net charge of the ion is -1, the oxidation number of the other atom (call it x) must be such that four times it and +3 add up -1:

4x + 3 = - 1

4x = -1 - 3

4x = - 4

x = - 1

In conclusion, the oxidation state of Cl in the ion is -1

3. Identify the oxidation state of Cl in Ba (ClO₂)₂ .

This is a neutral compound. Thus the overall oxidation number is 0.

The oxidation state of Barium, Ba, such as of the other members of the group 2, alkaline earth metals, is +2.

The oxydation state of oxygen, O, in ternary compounds is -2

Thus, calling x the oxidation state of Cl and taking in account the number of atoms in the compound:

+2 + 2x + 4(-2) = 0

2x + 2 - 8 = 0

2x = 6

x = +3

Therefore, the oxidation state of Cl in this compound is +3

4. Identify the oxidation state of Cl in ClF₄⁺

Fluor has oxidation state -1. Since there are four atoms, it contributes with 4 × (-1) = - 4

The overall charge of the ion is +1.

Thus, the oxidation state of Cl, x, is:

x - 4 = 1

x = 1 + 4

x = +5

Hence, the oxidation state of Cl in this ion is +5.

6 0

2 years ago

Read 2 more answers

How many moles are in 25.3 g of a sample of potassium nitrate (KNO3)?

aksik [14]

Answer:

25.3 g of KNO₃ contain 0.25 moles.

Explanation:

Given data:

Number of moles of KNO₃ = ?

Mass of KNO₃ = 25.3 g

Solution:

Formula:

Number of moles = mass/ molar mass

Molar mass of KNO₃:

KNO₃ = 39 + 14+ 16×3

KNO₃ = 101 g/mol

Now we will put the values in formula.

Number of moles = 25.3 g/ 101 g/mol

Number of moles = 0.25 mol

Thus, 25.3 g of KNO₃ contain 0.25 moles.

8 0

3 years ago

Important (question on k12 test)

monitta

Answer:

A new Dana system of classification contains 78 different classes of minerals based on composition and then further classified by type and group. To be considered a mineral, a substance must be an inorganic, naturally formed solid, with a specific chemical formula and a fixed internal structure. To test whether something is a mineral, there are several identification tests to which the substance is subjected, including its resistance to scratching, its density in comparison to water, its color, the degree of light it reflects, the color of the powdered mineral, its breakage pattern and its crystalline form.

Explanation:

4 0

3 years ago

Read 2 more answers

n the laboratory, two forms of sodium phosphate will be available (the monobasic monohydrate NaH2PO4·H2O, F.W. = 137.99 g/mol, a

const2013 [10]

Answer:

The compound you will use is the Dibasic phosphate

Explanation:

Simple phosphate buffer is used ubiquitously in biological experiments, as it can be adapted to a variety of pH levels, including isotonic. This wide range is due to phosphoric acid having 3 dissociation constants, (known in chemistry as a triprotic acid) allowing for formulation of buffers near each of the pH levels of 2.15, 6.86, or 12.32. Phosphate buffer is highly water soluble and has a high buffering capacity,

In this case the most efficient way is to disolve the dibasic compound which in the reaction with the water will form the monobasic phosphate.

To make the buffer you have to prepare the amount of distillate water needed, disolve the dibasic phospate, and then adjust with HCl or NaOH depending on the pH needed.

6 0

3 years ago