Back To Basics Science Flashcards
Atoms are made up of 3 particles
- neutrons- make up an atomic mass with protons and have no charge
-protons- positive charge in nucleus
-electrons- orbit nucleus in shells and have a negative charge
-protons and electrons in an atom are equal making the atom neutral
Element
Substances that cannot be broken down into any other substance
Each element is made up of its own type of atom
Isotopes
Atoms with same atomic number but different atomic mass
Atoms with same number of protons but different number of neutrons
Similar chemical properties but different physical properties
How are EM waves created
As a result of vibrations between an electric and magnetic field
Electromagnetic waves
- Radio waves
2.microwaves
3.infared
4.visible light
5.ultraviolet
6.x-rays
7.gamma rays
-Wavelength decreasing from 1-7
-Frequency increases from 7-1
2 types of radiation
Ionising radiation
Non-ionising radiation
Ionising radiation
-subatomic particles have enough energy to break away an electron from its atomic shell in an atom causing the atom to become charged or ionized
-e.g gamma rays/x-rays
Non ionising radiation
-low energy radiation
-not enough energy to remove an electron from an atom
-e.g. infared, ultraviolet
3 main mechanisms of heat transfer
-conduction: heat transfer through solids caused by collisions of free electrons and ions
-convection: heat transfer through fluids- liquids and gases =. Fluid is heated causing movement of particles via kinetic energy
-radiation- heat transfer through EM waves. Radiation is energy moving from one place to another via particles/waved
Electrons orbit
Electrons orbit the nucleus at very high speeds
Force of attraction between negatively charged electrons and positively changed protons keep electrons in orbit
Electron shells are also knows as orbits and are referred to by letters
Electron binding energy
Nucleus are held together by a strong force creating a binding energy
Measure of the amount of energy required to split the atom
Electrons are held in their orbits by binding energy
Closer the electrons to the nucleus the stringer the binding energy
Electron shells
Each shell has a max no. Of electrons it can hold
No. Increases as the distance of the shell from the nucleus increases
Max no of electrons a shell can hold can be calculated by 2nsquared
N=no of shell
Ionisation and electrons in atoms
An electron ca be removed from its orbit if its struck with an energy greater than its binding energy
This removed electron is now an ion - ionsiaruin
Inner shell vacancy
If ionisation occurs in a shell near to the nucleus an electron from an outer shell will drop down to fill in the inner shell vacancy
The orbit shells fill from the shells nearest to the nucleus outwards making it unstable
Which type of radiation from the EM spectrum can cause ionisation
Radio waves microwaves infared visible light UV light DO NOR have enough ENERGY for e- to penetrate through the skin so can’t cause ionisation
BUT…
X-rays and Gamma rays have ENOUGH ENERGY to knock out e- out of there shells
