1.5 More electron arrangement in atoms Flashcards
What is the formula to calculate the max number of electrons each shell can hold
2n^2 where n is the number of shells
SO there are 2 on the first, then 8 and then 18
Apart from the first energy level which only has an s sub level, what are the names of the other sub shells
s, p, d, f and these each have slight different energies.
Level 2 has an s and p sub level
Level 3 has s, p, and d sub level
What is the theory of quantum mechanics
. Developed during 1920s
. This describes the atom mathematically with an equation (the Schrödinger equation)
The solutions to this give the probability of finding an electron in a given volume of space called an atomic orbital
What is an atomic orbital
. Electrons are a cloud of negative charge, and they fill a volume in a space called its atomic orbital.
How are the concepts of main levels and sub levels included
. Different atomic orbitals have different energies. Each orbital has a number which tells us the main energy level it corresponds with, eg 1,2,3
. The atomic orbitals of each main level have different shapes which in turn have slightly different energies. These are the sub levels which are described by letters s,p,d,f
S has a shape with a circle with a diagonal line going across it
P has an infinity shaped sign
. D has 4 balloon shaped orbitals
What do the shapes of orbitals represent
. Represent a volume of space where there is a 95% probability of finding an electron and they influence the shape of molecules.
What orbitals are on each energy level
-1st energy level has a single s orbital
-2nd energy level has a single s orbital and three p orbitals of slightly higher energy
- Third energy level has a single s orbital, three p orbitals, 5 d orbitals of slightly higher energy still
How many electrons can each orbital hold
how many electrons can the s, p, and d sub levels hold
2 electrons
S holds one orbital, so two electrons
P holds three orbitals which hold two electrons each so there are 6 electrons in each P sub levels
D holds 5 orbitals which hold two electrons each so has a total of 10 electrons
What is spin
Electrons have a property called spin
. Two electrons in the same orbital must have opposite spins
. The electrons are represented by arrows pointing up or down to show different directions of spin
What are the 3 rules for allocating electrons to atomic orbitals
. Atomic orbitals of lower energy are filled first, so the lower main level is filled first and within this level, sub levels of lower energy are filled first.
. Atomic orbitals of the same energy fill singly before pairing up, this is because electrons repel each other.
. No atomic orbital can hold more than two electrons
How would you write the electronic structure for sodium which has 11 electron
What about for calcium with 20 electrons
1s^2, 2s^2, 2p^6, 3s^1
1s2 2s2 2p6 3s2 3p6 4s2.
Because the 4s subshell fills up before the 3d subshell as it is on a lower energy level
What is the electronic configuration for krypton with 36 electrons
1s^2, 2s^2, 2p^6, 3s^2, 3p^6, 4s^2, 3d^10, 4p^6
Why is the 4s orbital filled before the 3d
What happens in ions
Because it is of a lower energy so will fill up first.
However once it is full it has more energy than the 3d sub shell so in ions, electrons are lost from the 4s sub shell before the 3d sub shell
What happens in chromium and copper between the 3d and 4s subshell
. Electron configuration for chromium is 3d5 4s1 because usually there would be 4 electrons in the 3d shell and 2 in the 4s shell.
However, the 3d shell wants to have one electron in each of the 5 orbitals so can take an electron from the 4s shell to achieve this
. In copper there are 10 electrons in the 3d sub shell and 1 in the 4s shell. usually it would be 9 in the 3d shell and 2 in the 4s.
However the 3d wants to have a full valence shell so 2 electrons in each of the 5 orbitals so takes an electron from the 4s shell so achieve this.
