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
Electron configuration for ag
[Kr]5s1 4d10
Electron configuration for Au
[Xe] 6s1 4f14 5d10
Why does cr mo cu ag and au have different electron configs?
Due to the d orbital not being filled. they bring an electron from higher orbital like 4s
What is an excited state?
causes an electron to jump up to a higher energy orbital
What happens when the electron goes back to its ground state (the orbital that it came from )
it gives off energy in the form of heat/color/light
How can an electron be promoted to a higher energy shell or orbital?
absorbing a photon
How to find an element in an excited state using electron configuration
step 1. count up the super script to find that element
step 2. see if the electron configuration are normal that element. if one is off, then that one has the excited state.
How to solve questions like “which element corresponds to each of the following electron config?
just add up all the superscripts
If its like this [Kr] 5s1 4d5…. count up 1+5 plus 36 which is Kr
What is paramagentic
unpaired electrons. attracted to magnets
