Atomic Structure -Physical Chemistry Flashcards
What are protons and neutrons in the nucleus sometimes referred to and why
Nucleons and this is because they are found in the nucleus
How are protons and neutrons held together in the centre of an atoms
By strong nuclear force
How is strong nuclear force able to overcome repulsion between protons in the nucleus
Because it is much stronger than electrostatic forces but can only work over short distances
What does the letter Z represent
The atomic number
What does the letter A represent
The mass number
What do the number of electrons determine
It determines the chemical properties of an element and how it reacts
What does the atomic number define
The chemical identity of the element
What are isotopes
They are elements that have the same number of protons but different amount of neutrons
How is it that different isotopes of the same element will react chemically in the same way
As they have the same electron configuration
What is abundance
It’s how much if the element is present in the atomsphere
How many electrons can the 3rd she’ll hold
Up to 18
What is a mass spectrometer used to determine
The relative atomic mass of a substance
Why is the apparatus contained in a vaccum
To prevent the ions that are formed Colliding with molecules in the air
What happens in ionistation
The sample to be investigated is dissolved in a volitale solvent and forced through a hollow needle which is connected to the positive terminal of a high voltage supply, tiny positively charged droplets are produced as their electrons have been lost to the positive charge of supply. The solvent evaporates into the vaccum and the droplets get smaller in size till they become no more than one positively charged ion
What happens in acceleration
A negatively charged plate is used to attract the positively charged ion and the ions accelerate towards the plate at high speeds the highly charged and lighter ions will move at a higher speed
What happens in ion shift
The ions will pass through a negatively charged plate a beam will then form and travel along a tube known as a flight tube to the detector
What is detection in the mass spectrometer
When ions with same charge arrive at the detector the lighter ones will go first due to having higher velocities the flight times will be recorded. after the positive ions will pick up an electron from the detector and this will cause current to flow
What happens I. Data analysis
The signal fri. The detector is then passed to the computer and this will generate mass spectrum
What do different atomic orbitals have
They have different energies
Give the order of sub levels in the atomic orbitals
S P D F
Give the order of the atomic orbitals with their main level and sub levels
1s 2s 2p 3s 3p 4s 3d 4p 4d
Why is 3D after 4s
As it has a slightly higher enegry level
How many electrons do the a orbitals hold
2
How many orbitals do the P orbitals hold
6
How many electrons do the D orbitals hold
10
What property do electrons have
Spin
What is first ionisation energy
The amount of energy needed to remove one electron from an element in a gasesous sate
What is second ionisation enegry
The amount of energy needed to remove an electron from a positive Ion
Why is more enegry needed to remove second electron
As it is being removed from a + 1 ion
Why does ionisation enegry increase across a period
As the nuclear charge increases this due to more protons being added and so the attraction to the nucleus is stronger
Why does helium have the highest ionistation enegry
As there is no shielding and it’s electrons are very close to it’s nucleus
Why does ionistation enegry decrease down a group
Because the outer electrons are further away from nucleus and the attraction is less due to shielding from inner electrons
Although across a period ionisation enegry increases why does magnesium have a higher ionisation energy than aluminium
As aluminium outer electron is in the 3 p orbital and is further away from the nucleus so it’s easier to remove
What two things are measured for isotopes
Mass charge ratio
Abundance
Although they are electrons in the same orbital why does phosphorus have an higher ionisation energy than slicon
As in slicon it has a pair of electrons in it’s outer shell and because they pair up their is a repulsion and so it’s makes it easier to remove so the ionisation energy is smaller
Why do ionic compounds shatter easily
Because when they are given a sharp blow there structure dislodges and a a lattice of alternating positive and negative ions forms and the like charges come in contact and they repel
What two things are measured for isotopes
Mass charge ratio
Abundance
In the mass spec what does the last peak tell us
The relative molecular mass ion
Ie 86
Describe the structure and bonding in graphite
Layer of carbon atoms
Macromolecules with strong covalent bonds spread out throughout the structure
Weak van der waals forces between its atoms
Layers slide over one another
