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2 years ago

Which statements about the structure of the periodic table are true?

Chemistry

1 answer:

DiKsa [7]2 years ago

3 0

Answer:

The distribution of electrons in energy levels is responsible for the shape of the periodic table.

Explanation:

Henry Moseley in the 1900s re-stated the periodic law by changing the basis of the table to reflect more on the atomic number. The present law is therefore "the properties of elements are a periodic function of their atomic numbers".

Atomic number is the number of electrons in an atom and it is the same as the number of protons for neutral atoms.

In the table, elements having the same number of electrons in the outermost shell of their atoms are placed over one another in vertical columns. Each of the vertical column is known as a group or family while each of the resulting horizontal rows is known as period or row.

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What is the chemical formula for sodium sulfate?

yan [13]

Hello!

When finding the chemical formula of a compound, we will need to find the charges of each element/bond.

Looking at our period table, sodium has a +1 charge, written as Na 1+, and sulfate has a charge of -2, and it is written as SO4 2-.

Now, we need to make the charges equivalent. To do this, we need to "criss-cross" the charges. This means that sodium will need to additional atoms to make the charges equal, and sulfate will need one.

Therefore, the chemical formula for sodium sulfate is: Na2SO4.

5 0

2 years ago

Water is poured into a conical container at the rate of 10 cm3/sec. The cone points directly down, and it has a height of 20 cm

8090 [49]

Answer:

\frac{dh}{dt}_{h=2cm} =\frac{40}{9\pi}\frac{cm}{2}

Explanation:

Hello,

The suitable differential equation for this case is:

$\frac{dV}{dt}=10\frac{cm^3}{s}$

As we're looking for the change in height with respect to the time, we need a relationship to achieve such as:

$\frac{dh}{dt} = ?*\frac{dV}{dt}$

Of course, $?=\frac{dh}{dV}$ .

Now, since the volume of a cone is $V=\pi r^2h/3$ and the ratio $r/h=15/20=3/4$ or $r=3/4h$ , the volume becomes:

$V=\pi (\frac{3}{4} h)^2h/3= \frac{3}{16}\pi h^3$

We proceed to its differentiation:

$\frac{dV}{dh} =\frac{9}{16} \pi h^2\\\frac{dh}{dV} =\frac{16}{9 \pi h^2}$

Then, we compute $\frac{dh}{dt}$

$\frac{dh}{dt} = \frac{16}{9 \pi h^2}*\frac{dV}{dt}\\\frac{dh}{dt} = \frac{16}{9\pi h^2}*10\frac{cm^3}{s} =\frac{160}{9 \pi h^2}$

Finally, at h=2:

$\frac{dh}{dt}_{h=2cm} =\frac{160}{9\pi 2^2}\\\frac{dh}{dt}_{h=2cm} =\frac{40}{9\pi}\frac{cm}{s}$

Best regards.

4 0

2 years ago

Why is the moon unique

Ainat [17]

Answer:

Explanation:

well there is many things in our solar system and a moon is one of them. the moons in our solar system are big and small and orbit our planets. the moon is unique because it shines in the dark while it lets the sun shine in the light.

Thats what i would say but its an eh answer

8 0

2 years ago

Read 2 more answers

What is force? Why?

larisa [96]

In physics, a force is any interaction that, when unopposed, will change the motion of an object. A force can cause an object with mass to change its velocity to accelerate. Force can also be described intuitively as a push or a pull. A force has both magnitude and direction, making it a vector quantity.

4 0

2 years ago

The true absorbance for a 1.0 x 10 −5 M solution is 0.7526. If the percentage stray light for a spectrophotometer is 0.56%, calc

Korvikt [17]

Answer:

The percentage deviation is $\Delta M = 1.87$ %