Atomic Structure Flashcards
Define atom
The smallest part of an element that can exist.
All substances are made up of…?
atoms
The radius of an atom is …?
0.1 nm (1 x 1010 m)
The overall charge on an atom is…
zero/neutral
Define element
Contains only one type of atom
Substances found in the periodic table are…?
elements
Approximately how many elements are there?
100
Define isotope
An atom of the same element with different numbers of neutrons
Define radioactive decay
An unstable nucleus changes to become more stabe and gives out radiation
We cannot predict when a given atom will decay, this means that radioactive deacy is ….?
random
Define activity
Rate at which decay occurs
What are the units of activity?
Becquerels (Bq)
Define count rate
Number of decays recorded each second by a Geiger-Muller tube
Defne half life
The time taken for number of radioactive nuclei in a sample to halve OR time taken for count rate (or activity) from a sample to fall to half its initial value
Define contamination
The unwanted presence of materials containing radioactive atoms
Define irradiation
When an object is exposed to radiation
Does an irradiatied object become radioactive itself?
no
The process of radiation removing electrons from atoms to form ions is called…?
ionisation
If ionisation happens in DNA it can cause ___________ which may result in ____________
mutations, cancer
Define peer review
Checking of scientific results by other scientific experts
Define mass number
The total number of protons and neutrons in an atom
Define atomic number
The number of protons in an atom (number of electrons is the same in a neutral atom)