It is each of two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei, and hence differ in relative atomic mass but not in chemical properties; in particular, a radioactive form of an element.
Answer:
Explanation:
When an electron jumps from one energy level to a lower energy level some energy is released in the form of a photon.
The difference in energy between the two levels is the energy of the photon and that energy is related to the frequency of the photon by the Einstein - Planck equation:
Where,
- E = energy of the photon,
- h = 6.626×10⁻³⁴ J.s, Planck constant, and
- ν = frequency of the photon.
So, to find the frequency you must first find the energy.
The transition energy can be calculated using the formula:
Where E₀ = 13.6 eV ( 1 eV = 1.602×10⁻¹⁹ Joules) and n = 1,2,3,...
So, the transition energy between n = 4 and n = 3 will be:
- ΔE = - E₀ [ 1/4² - 1/3²] = - 13.6 eV [1/16 - 1/9] = 0.6611. . .eV
- ΔE = 1.602×10⁻¹⁹ Joules/eV × 0.6611... eV = 1.0591 ×10⁻¹⁹ Joules
Now you can use the Einstein - Planck equation:
- ν = 1.0591 ×10⁻¹⁹ J / 6.626×10⁻³⁴ J.s = 1.60×10¹⁴ s⁻¹ (rounded to 3 significant figures).
1) Acidic solution. An acidic solution has a high concentration of H+ ions.
2) Basic solution. A basic solution has a high concentration of OH- ions.
3) HCl chemical reaction.
![HCl+H_2O\rightarrow H_3O^++Cl^-](https://tex.z-dn.net/?f=HCl%2BH_2O%5Crightarrow%20H_3O%5E%2B%2BCl%5E-)
You can also write it as follows
![HCl+H_2O\rightarrow H^++Cl^-](https://tex.z-dn.net/?f=HCl%2BH_2O%5Crightarrow%20H%5E%2B%2BCl%5E-)
4) pH scale.
When the concentration of H+ is high, the solution is acidic. H+ lowers the pH of the solution.
Option D.
Answer:
make sure that the number of atoms on the left side of the equation equals the number of atoms on the right.
Explanation:
Answer is:
Less than the vapor pressure of pure water