Protons and neutrons are sometimes called nucleons because they are found in the nucleus.
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What force holds the protons and neutrons together in the centre of the atom?
Strong nuclear force. It is stronger than the electrostatic forces that hold protons and electrons together so it overcomes the repulsion between protons in the nucleus. It acts only over very short distances.
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What determines the chemical properties of an element and what sort of element it is?
The number of electrons and protons.
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Early theories model the electron as a minute solid particle. What do later theories show them as?
Clouds of negative charge; you can never say exactly where an electron is at any moment. You can merely state the probability that it can be found in a particular volume of space that has a particular shape.
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What are the steps in mass spectrometry?
(VIA IDD): Vacuum; Ionisation; Acceleration; Ion drift; Detection; and Data Analysis.
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What is the vacuum stage of mass spectrometry?
The whole apparatus is kept under a high vacuum to prevent the ions that are produced colliding with molecules in the air.
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What is the ionisation stage of mass spectrometry?
There are two types: electrospray and electron impact.
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What happens in electrospray ionisation?
The sample is dissolved in a volatile solvent and forced through a fine hollow needle connected to the positive terminal of a high voltage supply. This produces tiny positive droplets that have gained a proton from the solvent. The solvent evaporates
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What happens in electron impact ionisation?
The sample is vaporised and high energy electrons are fired at it from an electron gun, which is a hot wire filament with a current running through it that emits a beam of high energy electrons. This usually knocks off one electron from each particle
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What happens in the accleration stage of mass spectrometry?
The positive ions are attracted towards a negatively charged plate and accelerate towards it. Lighter ions and more highly charged ions achieve a higher speed.
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What happens in the ion drift stage of mass spectrometry?
The ions pass through a hole in the negatively charged plate, forming a beam and travel along a tube, called the flight tube, to a detector.
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What happens in the detection stage of mass spectrometry?
When ions with the same charge arrive at the detector, the lighter ones are first as they have higher velocities. The flight times are recorded. The positive ions pick up an electron from the detector, which causes a current to flow.
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What happens in the data analysis stage of mass spectrometry?
The signal from the detector is passed to a computer which generates a mass spectrum.
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What is the difference between high resolution spectrometry and low resolution spectrometry?
High resolution is to five decimal places; low resolution is only done to one decimal point.
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What causes orbitals to have different energies?
Their different shapes.
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What are the three rules for allocating electrons to atomic orbitals?
1) Atomic orbitals of lower energy are filled first; 2) Atomic orbitals of the same energy fill singly before pairing starts because of electron repulsion; 3) No atomic orbital can hold more than two electrons.
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List the shorthand electronic structures in ascending order of energy.
1s, 2s, 2p, 3s, 3p, 3d, 4s, 4p
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What are successive ionisation energies?
The energies needed to remove the electrons one by one from an atom, starting from the outer electrons and working inwards to leave just a nucleus.
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Why is the increase ionisation energies across a period not regular?
If the outer electron of an element is alone in a slighty higher energy level than the last electron of the element, it requires less energy to remove it. This is also true for when the outer electrons go from being single to being paired.
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Other cards in this set
Card 2
Front
What force holds the protons and neutrons together in the centre of the atom?
Back
Strong nuclear force. It is stronger than the electrostatic forces that hold protons and electrons together so it overcomes the repulsion between protons in the nucleus. It acts only over very short distances.
Card 3
Front
What determines the chemical properties of an element and what sort of element it is?
Back
Card 4
Front
Early theories model the electron as a minute solid particle. What do later theories show them as?
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