| What is an atoms mass made up of? | positively charged dense nucleus made of protons and neutrons
negatively charged electrons are in the space outside the nucleus |
| What is the mass spectrometer used for? | to determine the relative atomic mass of an element from isotopic composition
mass: charge ratio is used
atoms are bombarded with high energy electrons to produce positive ions |
| How is the emission spectra produced? | when photons are emitted from atoms as excited electrons return to lower energy levels |
| What does the emission line spectrum of hydrogen provide evidence of? | existence of electrons in discrete energy levels, that converge at higher energies
has a series of bright lines on a dark background (line spectrum) |
| What is the order of energy for where electrons are found? | energy level = s, p d
sub-level = 1, 2, 3
orbitals |
| How can ion charge be calculated? | no of protons - no of electrons |
| What are the relative masses and relative charges of the particles in an atom? | proton = 1 +1
neutron = 1 0
electron= 5*10^4 -1 = mass is negligible |
| What is the atomic number? what letter is used to represent it? | no of protons in the atom's nucleus
Z |
| What is mass number? what letter is used to represent it? | no of protons + neutrons
A |
| How would the mass number and atomic number be placed for a symbol of an element? | mass number on top (A)
Atomic number (Z) |
| What are ions? | charged particles formed when an atom loses / gains an electron |
| What is a positive ion + negative ion called? | cation
anion |
| What are isotopes? | different atoms of the same element w different number of neutrons
have the same chemical properties (React same) but diff physica properties (diff MP / BP) |
| Why do isotopes have the same chemical properties? | they have the same no of electrons
chemical reactions depend on no and arrangement of electrons |
| Why do isotopes have different physical properties? | bec of diff masses = atom move at different speeds |
| What is relative atomic mass? | Ar of an element is the average weighted mass of the isotope of an element when compared to the mass of 1/12th of an atom of carbon-12 |
| What is the formula for relative atomic mass? | isotope abundance * mass number / 100 |
| What is another name for the main energy level? | principal quantum number
symbol = n
2n2 |
| What is the general rule for filling the energy levels? | electrons must fill from the lowest energy - highest |
| what does frequency equal? | 1/wavelength
energy |
| What is the difference bw a line and continuous spectrum? | line = only some frequencies of light can be seen
continuous = all frequencies of light can be seen |
| How is the emission spectrum formed? (4) | 1) passing an electric discharge through a gas = electron gets promoted to a higher energy level
ground state -> excited state
2) bec the electron is unstable in the higher level it will fall down to a lower energy level
3) this extra energy is given out as a photon of light = line in spectrum
= evidence of electrons being in energy levels as the electrons can only have certain amount of energy
CONC= photon of light given out from electron when it goes from high energy level = low after being excited from an electric discharge |
| Where do all the visible region transitions occur for the emission spectrum? | when an electron falls down to level 2 |
| Where do all the UV region transitions occur for the emission spectrum? | Level 1 |
| What happens after the convergence limit? | lines merge to form a continuum
after this point, electrons can have any energy |
| what is the order of sub-levels from smallest to biggest? | s, p, d, f |
| What is the aufbau principle? | electrons fill sub levels from lowest energy upwards = lowest possible energy |
| What is an orbital? | region of space that has a high probability of having an electron
max 2 electrons |
| What are the shapes of the orbitals? | s = spherical
p = dumbbell shape (3p orbitals are at 90 degrees to eachother
d= 4 leaf clover |
| What are degenerate orbitals? | when all the orbitals have the same energy
eg: all the 3 2p orbitals |
| What is the pauli exclusion principle? (2) | max number of electrons in an orbital is 2
if there are 2 electrons they will have opposite spin |
| What is Hund's rule? | each electron fills each orbital separately first with the same spin = gives a lower energy and more stable |
| What are the 3 rules of filling out orbitals? | Aufbau's principle: electrons fill out from the lowest energy level first
Hund's rule: first fills out all the orbitals separately with the same spin
Pauli's exclusion principle: each orbital can only have 2 electrons and they will have different spins |
| which transition will give the shortest wavelength in the visible region? | infinity = level 2 |
| Why is copper and chromium an exception to the aufbau principle? | when half full or full shells are more stable than partially filled ones
so when the difference bw energy levels is small an electron can be transferred to a higher level
= more stable |
| What is the electron configuration for copper? | 1s2 2s2 2p6 3s2 3p6 4s1 3d5
this makes both the 4s and 3d sublevels half full = more stable |
| What is the electron configuration for Chromium? | 1s2 2s2 2p6 3s2 3p6 4s1 3d10
a full 3d shell is more stable |
