3.1.1 Atomic Structure Flashcards
What is the mass of a proton?
1
What is the mass of a neutron?
1.001
What is the mass of an electron?
0.000005
What is J.J Thomson’s discovery?
Electrons were smaller than at atom.
Came up with the plum pudding model- electrons were embedded within a positively charged ball of atoms.
What did Rutherford discover?
Atoms are mostly empty space with a core that is positively charged.
He done this by firing alpha particle at a gold foil and observing that some of the alpha particles bounced back.
What did James Chadwick discover?
The nucleus is made up of both protons and neutrons.
What is an isotope?
Different versions of the same elements with a different number of nuetrons
Define the relative atomic mass
The relative atomic mass (Ar) is the average mass of atoms of an element relative to the mass of an atom of carbon-12
How does nuclear charge vary across a period?
It increases by 1 as proton number increases
What happens to nuclear charge as we go down a group?
It increase as the number of protons increases
What is nuclear charge?
The collective charge of all protons in a nucleus.
As the electrons distance from the nucleus increases____
The forces it experiences decreases
Across a period, the distance between the nucleus and the outer electrons_____
Decreases, this is because the nuclear charge increases so it pulls the shells towards the nucleus
As we move down a group, the distance between the nucleus and the outer electrons______
Increase as the outer electrons are in a different shell.
What is shielding?
Each electrons shields some of the nuclear charge from the other electrons. An electron closer to the nucleus would shield the charge of a proton
As we move across a period, shielding____
Is the same
Down a group, the amount of shielding in the outer electrons…
Increases
What is ionisation energy
The energy required to remove one mole electrons from one mole of gaseous atom of that element.
As you go down a group, first ionisation energy…
Decreases. This is because the outer electrons become more shielded and further away from the nucleus so less energy is required to remove the electron
Across a period, first ionisation energy…
Increases.
This is because nuclear charge increases whilst shielding stays the same, therefore the outer electrons experience stronger attraction to the nucleus.
Why is there a dip in ionisation energy between magnesium and aluminium?
- There outer electrons are in different sublevels.
Magnesium: 3s
Aluminium: 3p
Therefore, as aluminium has a 3p orbital which is further from the nucleus and shielded from inner electrons it requires less energy.
Explain why there is a dip in ionisation energy between phosphorus and sulfur.
Both phosphorus and sulphur have electrons in the 3p orbital. However sulfur has one paired electron which experiences extra repulsion. Therefore requiring less energy then phosphorus.
what is stage 1 of mass spectrometry?
Ionisation:
the sample is first vapourised and an electron gun fires electrons knocking off one electron, making them 1+ ions.
what is stage 2 of mass spectrometry?
acceleration:
the positive ions are accelerated by an electric plate with the same kinetic energy. this means that heavier particles will be slower and lighter ones will move faster.
what is stage three of mass spectrometry?
Ion drift:
the ions are in a vacuum to stop them from slowing down, they carry on drifting toward the next stage.
What did dalton discover?
Elements react together in different proportion but always in whole number ratios.- found the existence of atoms
what is the last stage of mass spectrometry?
Detector:
The ions gain an electron from the plate. This movement of electrons creates a current which is detected by a computer which creating a mass spectra.
What experiment did Rutherford do?
He done this by firing alpha particle at a gold foil and observing that some of the alpha particles bounced back.
What is nuclear force?
Protons and neutrons are held together by this
What similar properties do isotopes have?
Same chemical properties
What is the mass number?
The number of protons and neutrons.
What is an ion?
At atom with a positive or negative overall charge
What is the atomic number?
The number of protons
Where does mass and atomic number go?
Mass number
Atomic number
What is the period table ordered by?
Proton number
