Core Knowledge-atomic structure Flashcards
(50 cards)
Define an atom
The smallest part of an element
All substances are made up of…?
Atoms
What is the radius of an atom?
0.1nm
What is The overall charge on an atom
Zero or neutral
Define an element
Contains only one type of atom
Define an isotope
An atom of the same element with a different number of neutrons
Define radioactive decay
An unstable nucleus changes to become more stable and gives out radiation
We cannot predict when an atom will decay, what does this mean that radioactive decay is?
Random
Define activity
Rate of which decay occurs
What are the units of activity?
Becquerels (Bq)
Define count rate
Number of decays recorded each second by w Geiger-Muller tube
Define half life
The time taken for a number of radioactive nuclei in a sample to halve or Time taken for count right (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 irradiatedobject become radioactive itself
No
What is the process of radiation removing electrons from atoms to form ions called?
Ionisation
What can happen if DNA is ionised?
Mutations which may result in cancer
Define peer review
Checking of scientists 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)
Where are electrons located in an atom?
Energy levels
Who came up with the plum pudding model of the atom
J J Thompson
Describe the plum pudding model
A ball of positive charge with negative electrons embedded in it
What experiment did Rutherford do
Alpha particle scattering
