A dog barks to alert his owner. What is the medium for the sound waves produced by the dog barking? lesson 4.01
A. Air
B. ground
C. water
D. the ocean

the atomic number will stay the same no matter how many electrons it has, so it doesn’t decrease nor increase. it’ll only change with a different number of protons

atomic mass = 39

number of neutrons = 20

number of protons= 19

electronic configuration = 1s2 2s2 2p6 3s2 3p6 4s1

the number of electron in first shell = 2

number of electrons in n=3 shell = 8

it is stable as it is in group 0 which have full outer shells of electrons