atomic structure Flashcards
what is a beta particle?
it is a high-speed electron emitted from unstable nuclei
what is an alpha particle?
it is an atoms that consists of 2 protons and 2 neutrons emitted from unstable nuclei
what is gamma radiation?
it is electromagnetic radiation emitted from unstable nuclei
what is the symbol for an alpha particle?
4
a
2
what is the symbol for a beta particle?
0
β
-1
define activity
the number of unstable atoms that decay per second in a radioactive source
define half-life
the average tiime taken for the number of unstable nuclei in a radioactive sample to halve
define nuclear fusion
the proccess where two small nuclei are forced together and join to form a heavier nucleus, releasing large amounts of energy as a result
define nuclear fission
the proccess in which certain nuclei ( U-235 and Pu-239 ) split into ywo fragments, releasing large amounts of energy as a result.
what is ionisation?
it is any proccess in which atoms or molecules become charged
describe the differences between the plum pudding model and the nuclear model.
in the plum pudding model the mass is evenly distributed across the whole atom whereas in the nuclear model the mass is concentrated in the nucleus, morover the positive charge occupies only a small part of the atom. this means that the nuclear model has a lot of empty space compared to the plum pudding model which is solid mass. another difference is in the plum pudding model the electrons are embedded into the positive mass, however in the nuclear model the elcetrons are orbiting around the positive mass.
what happens when an electron moves from one energy level to another energy level int he same atom?
when an electron absorbs electromagnetic radiation it turns into an exited state which allows the electron to move from a lower energy level to a higher energy level. when an electron moves/ falls to a lower energy level, it emits electromagnetic radiation and this is called de-excitation.
p x v is a constant
p ∝ 1/v
p is directly proportional to 1 over v
explain why the pressure in the gas decreases as the gas is compressed in a syringe
when the gas is compressed the particles are pushed nearer together this causes them to collide with each other and the syringe at a faster rate, however the average speed doesn’t change. the volume of the container decreases and particles have less space to move around, therefore collisions are more frequent so pressure increases
explain the differences in how the particles are arranged in solids, liquids and gases.
in solids the particles are in a regular pattern and a fixed position. This means they vibrate and have a strong force of attraction. whereas, liquid particles move at a range of speeds and are arranged in an irregular pattern. in a gas the particles move at a range of speeds in random directions. this means the particles are very far away from each other and have a weak force of attraction
