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3 years ago

How are elements labeled on the periodic table that have the same number of valence electrons?

Chemistry

1 answer:

aksik [14]3 years ago

8 0

Answer:

Explanation:

Elements that have most similar properties were placed in the same group on the periodic table and this is done based on the number of valence electron each of the element posses which allow them reach in a similar manner as a member of the same family. A group of element is placed on a a vertical column of the periodic table.

For all element with one valence electron they are labelled with 1A on the group, and are usually the first column followed by 2A until group 8.

1A element are known to be very reactive and form compounds with similar properties with other elements.

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luminum and oxygen react according to the following equation: 4Al(s) +3O2(g) --> 2Al2O3(s) What mass of Al2O3, in grams, can

Slav-nsk [51]

Answer: 8.7 grams

Explanation:

According to avogadro's law, 1 mole of every substance occupies 22.4 L at STP and contains avogadro's number $6.023\times 10^{23}$ of particles.

To calculate the moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text {Molar mass}}=\frac{4.6g}{27g/mol}=0.17moles$

$4Al(s)+3O_2(g)\rightarrow 2Al_2O_3(s)$

As oxygen is in excess, Aluminium is the limiting reagent and limits the formation of products.

According to stoichiometry:

4 moles of aluminium give = 2 moles of $Al_2O_3(s)$

Thus 0.17 moles of aluminium give= $\frac{2}{4}\times 0.17=0.085mol$

Mass of $Al_2O_3=moles\times {\text {molar mass}}=0.085\times 102g/mol=8.7g$

Thus the mass of $Al_2O_3(s)$ is 8.7 grams

8 0

3 years ago

In AG calculations, temperature is expressed in a. degrees Celsius. b. kelvins. c. degrees Fahrenheit, d. kilojoules.

schepotkina [342]

Answer:

The correct option is: a. degrees Celsius

Explanation:

The anion gap is the difference in the cations and anions in plasma, serum or urine, calculated from medical lab test results. It can be calculated by measuring the concentration of the anions or cations, which are expressed in millimoles/litre (mmol/L) or milliequivalents/liter (mEq/L).

The temperature in this test is expressed in degrees Celsius (°C).

6 0

4 years ago

a substance that undergoes a physical change like melting is still the same substance is it true or false

Juli2301 [7.4K]

the answer would be true

3 0

3 years ago

Read 2 more answers

What is the BEST definition for friction?

NARA [144]

Hello


                         its me

and alsooo

                                                         the awnser is

number 3 lol

4 0

3 years ago

Which of the following is a change from a more condensed to a less condensed state of matter? Freezing Condensing Evaporating So

3241004551 [841]

Evaporating.

This is because evaporation occurs for things such as water coming in contact with a heat source that cause molecules to run crazy and begin to go farther and farther apart, becoming steam and evaporation in the air.

Therefore, during the process of evaporation, molecules become less condensed.

Hope this helps!

8 0

3 years ago