1.2 Mass number, atomic number, isotopes Flashcards
What particle determines the chemical properties of an element and what sort of element it is
Electrons
What particle determines the chemical identity of an element
Protons
Atomic number= number of protons
What is the mass number
The sum of protons and neutrons in the nucleus.
Its the nucleons which are responsible for almost all of the mass in an atom because electrons weigh virtually nothing
What are isotopes
Every single atom of any particular element has the same number of protons in its nucleus, and therefore the same number of electrons.
However number of neutrons can vary.
Atoms with same number of protons but different numbers of neutrons are isotopes
How do different isotopes react compared to the original atoms
Why do isotopes have different mass numbers
. They chemically react In the same way as they have the same electron configuration
. Atoms of different isotopes of the same element vary in mass number because of the different number of neutrons in their nuclei
What is radioactivity
Isotopes of an element have different numbers of neutrons in their nuclei, and sometimes these isotopes are unstable so the nucleus breaks down giving off bits of the nucleus which is the cause of radioactivity
each radioactive isotope decays at a rate measured by their half life ( the time taken for half of its radioactivity to decay)
One well known radioactive isotope is carbon-14, why does the level of carbon 14 stay the same
. There is some in all living matter, eg it takes it in and out in the form of food and carbon dioxide so as a result the level of it stays the same
How does carbon dating work
Once all the living matter its in dies, carbon is no longer taken in and out of bodies etc so the radioactive carbon breaks down, and rate of reactivity decreases, so knowing the half life of carbon 14, scientists work backwards.
