CHEMISTRY: TOPIC 2 ATOMIC STRUCTURE
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CHEMISTRY: TOPIC 2 ATOMIC STRUCTURE - Leaderboard
CHEMISTRY: TOPIC 2 ATOMIC STRUCTURE - Details
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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 |
What happens after the convergence limit? | Lines merge to form a continuum after this point, electrons can have any energy |
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 |
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 |