Structure and Bonding - Week 1-6 Flashcards
What is the mass of an atom?
the mass of the nucleus
What makes up the nucleus?
Protons and neutrons
What is the relationship between Daltons and g mol^-1?
1 Da = 1 g mol^-1
What is the Avogadro constant?
Na = 6.02214x10^23 mol^-1
Defines how many (atoms/molecules/things) there are in a mole
What is the unit for atomic mass?
Daltons (Da)
What is charge measured in?
Coulombs (C) in SI units
Protons +1
Electrons -1
How is nuclear charge determined?
number of protons in the nucleus
What is the mass number?
Number of protons + electrons
(top number)
What 4 factors affect electrons within atoms?
Energy level
Orbital shape
Orbital direction
Spin
How are electrons energy levels grouped and shown?
Energy is quantised according to number of nodes (wiggles present in the electrons wave)
What does the number of nodes represent?
energy level
What does it mean when an electron has more nodes?
more energy
What are the 3 types of orbital shapes?
s orbital
p orbital
d orbital
How many nodes are present in a s orbital?
no visible nodes present
How many nodes are present in a p orbital?
one node visible
How many nodes are present in a d orbital?
2 nodes visible
How many orbitals are allowed in the s orbital and what is their direction?
Spherical (not directional)
Only one s orbital per energy level
How many orbitals are allowed in the p orbital and what is their direction?
Three orbitals allowed per energy level
Point along x, y, z axes
How many orbitals are allowed in the d orbital?
5 orbitals allowed per energy level
Which way do electrons spin?
Internal spin
Only one value of spin is allowed
Electrons can spin in two different directions
-> spin up
-> spin down
What are the 3 electron filling rules?
Aufbau rule - electrons occupy the lowest energy orbital
available
Pauli principle - maximum of 2 electrons per orbital - one
spin up the other down
Hund’s rule - for orbitals with the same energy orbitals
are occupied singly if possible - spreads
electrons out
Why do unstable nuclei undergo nuclear decay?
to become more stable
What is alpha decay?
the nucleus will eject a particle containing 2 protons and 2 neutrons
4 He
2 —> alpha particle
What is beta decay?
a neutron in an atom can split into a proton and an electron
proton stays in the nucleus but an electron leaves (emitted electron = beta particle)
0 e
-1 –> B particle
What is nuclear fission?
Nuclei can react by absorbing neutrons and splitting into two smaller nuclei.
What is nuclear fusion?
Nuclei of small atoms can combine to produce a larger nucleus.