P4 Flashcards
what are the 3 particles in an atom?
protons, neutron and electrons
where are protons, neutrons and electrons found?
protons & neutron: in the nucleus
electrons: in the shells
what happens when 2 of the same charged particles experience a force?
they repell
what happens when 2 of opposite charged particles experience a force?
they attract
what is the relative charge of a proton?
positive +1
what is the relative mass of a proton?
1
what is the relative charge of a neutron?
neutral, 0
what is the relative mass of a neutron?
1
what is the relative charge of an electron?
negative, -1
what is the relative mass of an electron?
1/2000th
what is the charge of an atom? why?
they are neutrally charged
-bcus their no. of protons = no. of electrons
what is the overall charge of the nucleus?
positive
equation: relative mass of an atom
protons+ neutron
what is the atomic number?
number of protons
what is the mass number?
protons + neutrons
what are isotopes?
atoms with the same number of protons but different number neutron
what is ionisation?
the process in which an atom becomes an ion
what is excitation?
when energy is provided by light and en electron goes to a higher energy level
n.d what is relaxation?
what are 2 reasons for ionisation? Check
- another electron rushes past the atom with lots of energy and collides, with the atom and gives some of its energy within the atom and the electron has enough energy to escape
2, light of enough energy strikes the atom (e.g ultraviolet light)
what did Democritus come up with in 400BC?
everything is composed of atoms
what did John Dalton come up with? in what year?
- all matter is composed of atoms
- atoms can’t be subdivided or destroyed
- 1803
what did JJ Thompson come up with? what year?
The Plum Pudding Model
- 1904
what 3 things does the plum pudding model consist of?
- a positive ‘blob’
- negatively charged electrons scattered inside
- removing an electron made an ion
give 3 characteristics of Alpha particles
- positively charged
- light weight
- fast
what happens to the Fluorescent screen when alpha particles hit it?
it glows
Give 3 results of the alpha particles experiment
- most of the alpha particles passed straight through
- some would be deflected/ change direction
- a few would bounce back
what did it mean when most of the alpha particles went straight through?
means atoms are mostly empty space
What did it mean when some of the alpha particles deflected/ changed direction?
it meant the centre of the atoms are positively charged
what did it mean when a few alpha particles bounced straight back?
the centre of the atom is very small and dense, with a positive charge
what charge do alpha particles have?
positive
what charge does a gold atom have?
no charge, it’s neutral
what is the plum pudding model.
a ball of positive charge with negative electrons randomly embedded
what are 2 main changes to the atomic model the alpha scattering experiment resulted in?
mass: concentrated in the centre
charge: positive charge at the centre
who discovered the 1st chemical element?
Marie Curie
What did Marie Curie name the first chemical element?
Polonium
- after Poland
When does Radioactivity occur?
when the nucleus of an atom is unstable
what are the 4 types of nuclear radiation?
- order they were discovered
Alpha
Beta
Gamma
Neutron