DAT Chemistry chapter 2 Flashcards
How to find number of electrons
Do proton number minus the ion
How to write down electron configurations with ions?
Ex Ca2+
You take away the ion number from the outermost shell first. So take away from the 4s
Formula for l (quantum number)
n-1. From zero all the way to n-1. Ex
n=3. L could be any number between 0,1,2
How to find ml (quantum number)
look at l and do negative to positive
Ex. l= 3
-3,-2-1,0,1,2,3
What does l tell you (quantum number)?
the subshell (type of orbitals) l= 0 (s) l= 1 (p) l=2 (d) l=3 (f)
What is valence electrons
electrons in the atoms outermost shell
what is core electrons
atoms buried inside the inner shell
How to find valence electrons using electron config
Look at the shells that are furthest away and count up their electrons
Ex. 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p5
The 4 is the shell that is furthest away! so add up the electrons in the 4 shell. Which is 5+2=7
7 V.E
Exception to counting valence electrons using electron configurations
if element that you are looking at is in the D block, then you can count its V.E.
Like Ti
1s2 2s2 2p6 3s2 3p6 4s2 3d2
In cases like this…. you can the electrons from the D block! so V.E would be 4
What is aufbau principle?
electrons fill the lowest energy orbitals first
What is hunds rule
dont pair up electrons until you have to
What is pauli exclusion principle?
no two electrons in the same atom can have the same four quantum numbers.
Electron configuration for Cr
[Ar] 4s1 3d5
Electron configuration for Mo
[Kr] 5s1 4d5
Electron configuration for Cu
[Ar} 4s1 3d10
