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3 years ago

Atomic size generally _____.

Chemistry

2 answers:

Lunna [17]3 years ago

4 0

A. Increases as you move from left to right across a period

mafiozo [28]3 years ago

4 0

Atomic size generally

D. decreases as you move from left to right across a period

elements are classified into periods based on the number of energy shells.

elements that have the same number of energy shells fall into the same period.

as you go from left to right across a period, the atomic number increases. Atomic number is the number of protons. In ground state atoms the protons and electrons are the same.

so as you go across a period, the number of protons and electrons increase.

protons are positively charged and located in the nucleus. Electrons are negatively charged and are in energy shells. With higher number of protons in the nucleus, higher the positive charge in the nucleus. Then the force of attraction from the nucleus towards the electrons in the energy shells are higher.It will pull the energy shells more towards the nucleus making the atomic size smaller.

therefore atomic size decreases as you move from left to right across a period

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Perform the following operationand express the answer inscientific notation.7.00x10^5 - 5.00x10^4

11Alexandr11 [23.1K]

Taking into account the scientific notation, the result of the subtraction is 6.5×10⁵.

<h3>Scientific notation</h3>

First, remember that scientific notation is a quick way to represent a number using powers of base ten.

The numbers are written as a product:

a×10ⁿ

where:

a is a real number greater than or equal to 1 and less than 10, to which a decimal point is added after the first digit if it is a non-integer number.
n is an integer, which is called an exponent or an order of magnitude. Represents the number of times the comma is shifted. It is always an integer, positive if it is shifted to the left, negative if it is shifted to the right.

<h3 /><h3>Subtraction in scientific notation</h3>

You want to subtract two numbers in scientific notation. It should be noted that when the numbers to be added do not have the same base 10 exponent, the base 10 power with the highest exponent must be found. In this case, the highest exponent is 5.

Then all the values are expressed as a function of the base 10 exponent with the highest exponent. In this case: 5.00×10⁴=0.500×10⁵

Taking the quantities to the same exponent, all you have to do is subtract what was previously called the number "a". In this case:

7.00×10⁵ - 0.500×10⁵= (7.00- 0.500)×10⁵= 6.5×10⁵

Finally, the result of the subtraction is 6.5×10⁵.

Learn more about scientific notation:

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3 0

1 year ago

In this chemical Formula for Ammonia, the Subscripts indicate what?

zubka84 [21]

Answer:

Explanation:

B. There are two atoms of Nitrogen and two atoms of Hydrogen combined to make Ammonia.

7 0

2 years ago

As with other ionic compounds, potassium bromate, KBrO3, dissociates into ions when it dissolves in water. If 13.8 g of KBrO3 is

chubhunter [2.5K]

Answer:

ΔH of dissociation is 38,0 kJ/mol

Explanation:

The dissociation reaction of KBrO₃ is:

<em>KBrO₃ → K⁺ + BrO₃⁻ </em>

This dissolution consume heat that is evidenced with the decrease in water temperature.

The heat consumed is:

q = CΔTm

Where C is specific heat of water (4,186 J/mol°C)

ΔT is the temperature changing (18,0°C - 13,0°C = 5,0°C)

And m is mass of water (150,0 mL ≈ 150,0 g)

Replacing, heat consumed is:

q = 3139,5 J ≡ 3,14 kJ

13,8 g of KBrO₃ are:

13,8 g×(1mol/167g) = 0,0826 moles

Thus, ΔH of dissociation is:

3,14kJ / 0,0826mol = <em>38,0 kJ/mol</em>

I hope it helps!

3 0

2 years ago

A student sees an absorbance a=1.140 for his solution that has a concentration of c=1.50*10-4 m using 0.50 cm cuvette. what is t

777dan777 [17]

The molar extinction coefficient is 15,200 $M^{-1} cm^{-1}$ .

The formula to be used to calculate molar extinction coefficient is -

A = ξcl, where A represents absorption, ξ refers molar extinction coefficient, c refers to concentration and l represents length.

The given values are in required units, hence, there is no need to convert them. Directly keeping the values in formula to find the value of molar extinction coefficient.

Rewriting the formula as per molar extinction coefficient -

ξ = $\frac{A}{cl}$