Answer:
When the electron changes levels, it decreases energy and the atom emits photons. The photon is emitted with the electron moving from a higher energy level to a lower energy level. The energy of the photon is the exact energy that is lost by the electron moving to its lower energy level.
Explanation:
Answer:
Strontium
Explanation:
The atomic number of strontium is 38.
It has 38 electrons.
It is alkaline earth metal. It has two valance electrons.
Strontium loses its two electrons and form cation with +2 charge.
Electronic configuration;
Sr₃₈ = [Kr] 5s²
The valance electrons present in 5s are lost by strontium atom and form Sr⁺² cation.
it is yellowish-white metal.
It is highly reactive.
It form salt with halogens.e.g
Sr + Br₂ → SrBr₂
IT react with oxygen and form oxide.
2Sr + O₂ → 2SrO
this oxide form hydroxide when react with water,
SrO + H₂O → Sr(OH)₂
With nitrogen it produced nitride,
3Sr + N₂ → Sr₃N₂
With acid like HCl,
Sr + 2HCl → SrCl₂ + H₂
Answer:
B
Explanation:
This is because the periodic table is designed this way.
Answer:
c) the study of matter and the changes it undergoes
Explanation:
Chemistry -
It is the sub topic of science , dealing with the study of matter , the properties of matter , the type of interaction between the particles of matter , the reason for the particle of matter to combine and separate in order to form new substance .
The basic concepts of chemistry are applicable on the day to day activities.
Hence, from the given options , the correct statement is c) the study of matter and the changes it undergoes.
PH + pOH = 14
pH
= 14 - pOH
= 14 - 11
= 3
pH = 3
- lg [H+] = 3
[H+]
= 0.001
= [HNO3]
= 1 x 10-3 M
