Atoms Flashcards
What does half-life mean?
The half-life of a radioisotope is the amount of time it takes a radioactive isotope to decay to half its original value.
What does radioactive decay mean?
the process where an unstable atom loses energy through radiation. These can be emitted through alpha, beta and gamma rays.
Sub-atomic Particles
neutrons, protons and electrons
Name the charge of sub-atomic particles
Neutrons - neutral
Protons - positive
Electrons - negative
What is a nucleus
A nucleus is the centre of an atom and contains protons and neutrons. These particles are held together through very strong forces.
What is an isotope?
An isotope is an atom of the same element that differs in the number of neutrons, hence affecting its total mass.
What is the atomic number?
The atomic number is found on the bottom left-hand side of the element symbol and indicates its number of protons and electrons.
What is the mass number?
The mass number is the sum of the protons and neutrons in the nucleus and is indicated on the top left-hand side of the elemental symbol
What are protons?
Protons are positively charged particles found in the nucleus of an atom
What are neutrons?
neutrons are particles with no electrical charge that are found in the nucleus of an atom
What are electrons?
Electrons are negatively charged particles that orbit the nucleus in shells. The further shell they are in = the more energy they have. Electrons are very light and move aorund very quickly.
What are valence electrons?
Valence electrons are electrons found in the outermost shell. These valence electrons contain the most energy
Draw and label a diagram of an atom
List the number of protons, electrons and neutrons using the lithium atom. This atom has an atomic mass of 6.941 and a atomic number of 3.
Lithium has 3 protons, 3 electrons and 3.941 neutrons.
What process do particle equations represent?
Radioactive decay
During radioactive decay mass or charge can…..
neither be created nor destroyed
What must the total mass of particles equal after nuclear decay?
The sum of the masses of the particles before the nuclear decay
What type of decay has occurred if the mass is the same but the atomic number increases?
Beta decay has occurred and an electron has been added.