Basic chemistry Flashcards
what are the seven diatomic elements and what are their states at room temperature
(gas) oxygen
(gas) hydrogen
(gas) fluorine
(greenish gas) chlorine
(red liquid) bromine
(gas) nitrogen
(purple volotile solid) iodine (iodine can sublime directly into a gas)
what are covalent bonds (1 point)
a sharing of electrons, since they have same electronegativeily , hydrogen + hydrogen is a non-polar covalent bond
what are ionic bonds
they are assosicated with a tranfer of electrons, typically contain a metal and a non-metal
ploar covalent bond
electrons are shared unequally
if electronegativity different is considered to be equal to or more than 0.5 its polar, if its less its usually non-polar
what is a pure substance
has a constant composition, can be elements, compounds
what is a mixture
a combination of multiple pure substances, and can have variable composition
what is a homogenous mixture
mixture where the pure substances mix together (e.g. salt water), you don’t see the two disinguishable parts
what is a heterogenous mixture
mixture where the pure substances don’t mix together (e.g. oil and water, sand and water)
physical change vs chemical change
chemical identity changes in a chemical change,
phyiscla propoerties
boiling point
melting point
ductility
malleability
colour
viscosity
density
mass, weight, volume
chemical properties
flammability
corrosive
combustible
explosive
colour changing
pH
law of conservation of mass
matter cannot be created or destroyed in a chemical reaction.
law of definite proportions
the masses of each element in a given compound have constant composition.
law of multiple proportions
the ratio of the masses of the 2nd element for different compounds can be reduced to whole numbers.
when is an atom negative
more electrons and protons
when is an atom positive
more protons than electrons
what is an ion
a particle with an unequal number of protons and electrons
what are cations
ions with positive charges, more protons than electrons, metals typically form cations
what are anions
ions with negative charges, more electrons than protons non-metal typically form anions.
what is a molecule
a molecule is a particle with multiple atoms
how to find no. of electrons
is equal to atomic number minus the charge of the species.
how to find no. of protons
is equal to atomic number of element
how to find the no. of neutrons
difference between mass number an atomic number
top number on elements
atomic number