<span>The energy (E) per photon is expressed by Planck's equation: E = hf, where f is
the frequency and h is Planck's constant, experimentally determined to be
6.625 * 10**-34 joule-seconds. So to find E, we multiply h by the frequency
and obtain E = hf = (6.625 * 10**-34)(7.0 * 10**14) = 46.375 * 10**-20 joule
or in standard notation, E = 4.6375 * 10**-19 joule per photon.
Hope this answers your question.Sorry if I calculated wrong.</span>
Halogens (atoms with 7 valence electrons) and Hydrogen
or generally, atoms with their shells almost full
Answer:
Density is a physical property that is determined by dividing the mass of a given amount of a substance by its volume.
Explanation:
Those substances which has pH less than 5 are more acidic than Honeybee Venom. Some of them are listed below along with their pH scale,
1) <span>Acid rain and Tomato Juice has a pH of 4.
2) Soda and Orange Juice has a pH of 3.
3) Vinegar and Lemon Juice has pH of 2.
4) Gastric acid has a pH of 1.
5) Battery Acids have pH of zero.</span>
Potassium oxide: K₂O.
There's no need for prefixes since K₂O is an ionic compound.
<h3>Explanation</h3>
Find the two elements on a periodic table:
- Potassium- K- on the left end of period four.
- Oxygen- O- near the right end of periodic two.
Elements on the bottom-left corner of the periodic table are metals. Those on the top-right corner are nonmetals.
- Potassium is a metal,
- Oxygen is a nonmetal.
A metal and a nonmetal combine to form an ionic compound. Potassium oxide is likely to be an ionic compound. It contains two types of ions:
- Potassium ions: Potassium is group 1 of the periodic table. It is an alkaline metal. Like other alkaline metals such as sodium Na, potassium K tends to lose one electron and form ions of charge +1 in compounds. The ion would be K⁺.
- Oxide ions from oxygen: Oxygen is the second most electronegative element on the periodic table. It tends to gain two electrons and form the oxide ion
when it combines with metals.
The two types of ions carry opposite charges. They shall pair up at a certain ratio such that they balance the charge on each other. The charge on each
ion is twice that on a
ion. Each
would pair up with two
. Hence the subscript in the formula:
.
There are two classes of compounds:
- Covalent compounds, which need prefixes, and
- Ionic compounds, which need no prefix.
Prefixes are needed only in covalent compounds. For instance in the covalent compound carbon dioxide
, the prefix di- indicates that there are two oxygen atoms in the formula
. However, there's no need for prefix in ionic compounds such as
.