1.2 Basic ideas about Atoms Flashcards
What are the three fundamental parts of atoms?
Protons
Neutrons
Electrons
What is the charge and mass of a Proton?
+1
1
What is the charge and mass of a Neutron?
0
1
What is the charge and mass of an Electron?
-1
Negligible
Atomic Number
The number of protons in the nucleus of an atom
Mass Number
The number of protons + the number of neutrons in the nucleus of an atom
Isotopes
Are atoms that have the same number of protons but different numbers of neutrons
Ion
Is a particle where the number of electrons does not equal the number of protons
What is the overall charge of an atom?
0 or neutral
α - particles
Have a nucleus of 2 protons and 2 neutrons, therefore positively charged
β - particles
Are fast moving electrons, therefore negatively charged
γ - rays
Are high energy electromagnetic radiation, therefore no charge
What are α - particles stopped by?
A few cm of air or a thin sheet of paper
What are β - particles stopped by?
5mm thick sheet of aluminium
what can γ - rays pass through?
Several cm of lead or more than a meter of concrete
What is the most ionising type of radiation
α - particles
Half-life
Is the time taken for half the atoms in a radioisotope to decay
Two consequences for living cells exposed to ionisation?
The DNA may be damaged causing the cell to not function in the way it should or at all
Name three beneficial uses of radioactivity?
Medicine (Cobalt-60 in cancer treatments, radiotherapy)
Radio-dating (Carbon-14’s half life is used to calculate the age of plant and animal remains)
Industry analysis ( Measuring the thickness of sheets of foil)
Atomic orbital
Is a region in an atom that can hold up to two electrons with opposite spins
How many electrons can an s subshell hold?
2
How many electrons can a p subshell hold?
6
How many electrons can a d subshell hold?
10
How many electrons can a f subshell hold?
14
What shape are p orbitals?
Dumbbell shaped lobes (infinity symbol)
How many planes do p orbitals come in?
3
px, py, pz
Electronic Configuration
Is the arrangement of electrons in an atom
First Ionisation Energy
Is the energy required to remove one electron form each atom in one mole of its gaseous atoms.
Shielding Effect
Is the repulsion between electrons in different shells. Inner shell electrons repel outer shell electrons
Successive Ionisation Energies
Is the measure of energy needed to remove each electron in turn until all the electrons are removed from an atom
A large increase in ionisation energies shows that
An electron has been removed from an new shell closer to the nucleus
Light is a form of … radiation
Electromagnetic
What is electromagnetic radiation?
Energy travelling as waves
The frequency of electromagnetic radiation is … to energy
Directly proportional
The frequency of electromagnetic radiation is … to wavelength
Indirectly proportional
Between what wavelengths does the visible spectrum appear?
400nm and 700nm
Electromagnetic spectrum order (from lowest to highest wavelength)
Gamma ray, X-rays, Ultraviolet, Visible, Infrared, Microwaves, Radio waves
In the visible spectrum the smaller wave lengths are a … colour
purply blue
In the visible spectrum the larger wave lengths are a … colour
redy pink
Emission spectra
Electrons gain energy and rise to higher energy levels, when they fall they release the energy, depending on the distance they fall they release different wavelengths.
Lyman series falls to which level of n?
1
Balmer series falls to which level of n?
2
Paschen series falls to which level of n?
3
Convergence limit
Is when the spectral lines become so close together they have a continuous band of radiation and separate lines cannot be distinguished
Which series Lyman, Balmer or Paschen is in the visible spectrum?
Balmer
Electronic transition
Is the movement of an electron from one energy levels to another
Spectral lines
Are the lines emitted by falling electrons
When a atom emits an alpha particle its mass number … and its atomic number …
decreases by 4
decreases by 2
When an atom emits a beta particle its mass number … and its atomic number …
stays the same
Increases by 1
