Atoms & Molecules Flashcards
what is an element
pure substance that cannot be broken down into 2 or more simpler substances by chemical processes
what are atoms
smallest particles of an element that have the chemical properties of that element
*most of the atom is empty space
in terms of relative mass and charge
what are the differences among protons, neutrons and electrons
p:
relative mass - 1
relative charge - 1+
n:
relative mass - 1
relative charge - 0
e:
relative mass - 1/1840
relative charge - 1-
what are protons and neutrons collectively known as
nucleons
what is the relationship between protons and electrons in an atom
the number of protons and electrons are always equal (unless it is an ion)
2 points, 2 explanations
describe and explain the behaviour of protons and electrons in an electric field
electrons deflected towards positively charged plate, protons deflected towards negatively charged plate
since opposite charges attract, an electron is negatively, a proton is positively charged
electrons deflected to a larger extent than protons
mass of an electron is much smaller than that of a proton
describe and explain the behaviour of neutrons in an electric field
neutrons not deflected in electric field
neutrons are neutral and have no charge
what do A and V represent in the nuclide notation ᴬᵥX
A: mass/nucleon number
V: proton/atomic number
*periodic table representation is opposite of nuclide notation
*each element has a unique proton number
what is proton/atomic number
number of protons in the atom
what is mass/nucleon number
total number of protons and neutrons in the atom
why is there the same number of protons as electrons in an atom
an atom is electrically neutral (refer to electric field)
what are isotopes
atoms of the same element with the same number of protons but different number of neutrons
*they have same chemical properties but different physical properties
why do isotopes have similar chemical properties
atoms have same number of valence electrons and only valence electrons are involved in chemical reactions (valence electrons give atoms their chemical properties)
why do isotopes have different physical properties
they have different masses due to different number of neutrons
(results in different physical properties like melting/boiling points, densities)
3 points
what are characteristics of electron shells
electron shells are numbered in ascending order going outwards from nucleus
each electron shell can hold a maximum number of electrons (2.8.8 for first 20 elements)
electrons fill the innermost shell before moving on to the next outer shell
*valence electron shells must have electron(s) in them
