3.1.1 Atomic structure Flashcards
What is the definition of Ar?
Weighted average mass of an atom of an element taking into account all naturally occurring isotopes relative to 1/12th the mass of an atom of 12C.
What is the definition of Mr?
Mass of a molecule relative to 1/12th the mass of an atom of 12C.
What is the definition of mass number?
The number of protons and neutrons
What is the definition of atomic number?
The number of protons
What is an isotope?
An atom of an element with the same number of protons but different numbers of neutrons.
State the sub-shells in order of their increasing energy up to 4p
1s^2 2s^ 2p^6 3s^2 3p^6 4s^2 3d^6 4p^6
What is the definition of electrostatic force of attraction?
The attractive or repulsive force between two electrically charged objects
What is a simple molecular structure?
It is composed of small molecules, with small groups of atoms strongly held together by covalent bonding.
What is a macromolecular structure?
Large numbers of atoms are linked in a regular 3D arrangement by covalent bonds.
Give 2 examples of macromolecular structures
Diamond and silicon dioxide (silica)
Give three examples of simple molecular structures
Chlorine (CL2), water (H2O), ammonia (NH3) and Sulfuric acid (H2SO4)
What factors affect ionisation energy?
Nuclear charge, distance from nucleus and shielding
What is first ionisation energy?
The energy needed to remove 1 electron from each atom in 1 mole of gaseous atoms to form 1 mole of gaseous 1+ ions.
What is nuclear charge?
The more protons there are in the nucleus, the more positively charged the nucleus is and the stronger the attraction for the electrons.
What does a high ionisation energy mean?
There’s a high attraction between the electron and the nucleus and so more energy is needed to remove the electron.
What is second ionisation energy?
The energy needed to remove 1 electron from each ion in 1 mole of gaseous 1+ ions to form 1 mole of gaseous 2+ ions.
What did John Dalton describe atoms as?
Solid spheres
In 1897, what did J.J Thomson discover?
The electron
What was J.J Thomson’s model called?
Plum pudding model
Who conducted the gold foil experiment in 1909?
Ernest Rutherford, Hans Geiger and Ernest Marsden
What did Ernest Rutherford and his students do in the gold foil experiment, and what happened?
They fired positively charged alpha particles at a very thin sheet of gold. Most of the particles passed straight through the gold with only a small number being deflected backwards.
How is electron impact ionisation done?
The sample being analysed is vaporised and then high energy electrons are fired at it. The high energy electrons come from an ‘electron gun’ which is a hot wire filament with a current running through it that emits electrons. This usually knocks off one electron from each particle forming a 1+ ion
How do you work out the number of neutrons of an element/isotope?
Take the mass number away from the atomic number
How do you work out the number of electrons and protons of an element/isotope?
It’s the same number as the atomic number for both protons and electrons
Hydrogen, deuterium and tritium are all isotopes of each other.
Identify one similarity and one difference between these isotopes.
Similarity - They’ve all got the same number of protons/electrons.
Difference - They all have different numbers of neutrons.
Deuterium can be written as 2 H
1
Determine the number of protons, neutrons and electrons in a deuterium atom
1 proton, 1 neutron (2-1), 1 electron
What is the definition of isotopic mass?
Weighted average mass of an isotope of an element relative to 1/12th the mass of an atom of 12C.
