The elements that have the same valence are, mainly, in the same principal groups (principal columns) of the periodic table.
The principal columns are 1, 2, 13, 14, 15, 16, 17 and 18.
For example:
1) the elements with valence 1+ are in the first column:H, Li, Na, K, Rb, Cs, Fr.
2) The elements with valence 2+ are in the second column: Be, Mg, Ca, Sr, Ba, Ra.
3) The elements with valence 2- are in the column 16: O, S, Se, Te, Pb
But also those elements may have other valences: S, Se and Te, have also valences 2, 4 and 6. And Pb have valences 2 and 4.
4) The elements with valences 1-, 1, 3, 5 and 7 are in the column 17: Cl, Br, I, At.
F, the first element of group 16, has valence 1- and 1+
Answer:
Mg * ignore the division line
Explanation:
Mg has an atomic number of 12.
14 neutrons + 12 protons = mass number of 26
Answer:
0.0000101 grams.
Explanation:
First of all, use Avogadro's number to convert from molecules to moles.
Avogadro's number is 6.02 x 10^23.
Second of all, to convert from moles to grams, find the substance formula of phosphorus trichloride. After finding the substance formula, then find the molar mass of phosphorus trichloride.
Phosphorus trichloride is PCl3
Now find the molar mass of PCl3
P = 31.0 amu
Cl = 35.5 amu
They are three chlorine atoms and one phosphorus atom. So you do this.
31.0(1) + 35.5(3) = 137.5 g/mol
Now use dimensional analysis to show your work
4.6 x 10^16 grams of PCl3 * 1 mol/ 6.02 x 10^23 * 137.5 g/mol / 1 mol
The grams and the moles cancel out.
So now do [(4.6 x 10^16) / (6.02 x 10^23)] x 137.5
and you will get 0.000010507
4.6 has the fewest digits which is 2.
So use sig figs and the answer rounds to the nearest millionths.
0.000010507 rounds to 0.0000101
So the final answer is 0.0000101 grams(don't forget the units)
Hope it helped!
<span>fluorescence
</span>The glow emitted by a substance exposed to external radiation is called <u>fluorescence</u>
There are three types of heat transfer or heat propagation; conduction, convection and radiation. Heat transfer is the process by which heat projects externally however, depending on the temperature and pressure. Also called the movement of heat from a low temperatured state which increases as heat progresses.
Conduction is the heat transfer by contact, immediate contact.
Convection is the transfer of heat through air and water.
<span>Radiation is the transfer of heat regardless of the presence of atoms or particles. </span><u>
</u>
POH + pH = pKw
pOH + pH - pH = pKw - pH
pOH = pKw - pH.
The correct equation used to calculate pOH would be C. pOH = pKw - pH.