Chemistry Flashcards
Describe the structure of an atom.
A central nucleus containing protons and neutrons, surrounded by a cloud of electrons in shells.
Where is most of the mass in an atom?
In the nucleus, you can almost ignore the mass of electrons when estimating.
What is the atomic number?
The number of protons in the atom.
What is the mass number?
The number of protons plus the number of neutrons.
How can an atom have no charge?
It has an equal number of protons and electrons.
What is the formula for the number of electrons that can exist in each shell?
2*n^2, where n = number of the shell from inside out.
How would one write the configuration of electrons in eg. potassium?
You write the number in each shell, separated by a comma, eg. 2,8,8,1.
What are isotopes?
Isotopes are atoms of an element with the same number of protons, but different number of neutrons. They have different mass numbers.
How can you identify the chemical composition of something you can’t touch, like a star?
You can determine the chemical composition from a spectra, you look at the light because each element have different combinations.
What does a mass spectrometer do?
It identifies isotopes and the structure of molecules.
What is ‘Relative atomic mass’ (RAM)?
The average mass of 1 atom of an element, taking into account all of its isotopes and their relative abundances, relative to 1/12th the mass of a carbon-12 atom.
What is ‘Relative isotopic mass’ (RIM)?
The mass of an atom of 1 isotope relative to 1/12th the mass of a carbon-12 atom.
What is ‘Relative molecular mass’ (RMM)?
The average mass of 1 molecule of a compound, found by calculating the sum of the relativee atomic masses of the constituent atoms of the molecule.
What determins which element the atom is classified as?
The number of protons.
40
Ar
18
What are these numbers?
40 - Mass number
Ar
18 - Atomic number
Protons = 18
Neutrons = 22
Electrons = 18
