Atoms Flashcards
all substances are made of…
atoms
the nucleus contains…
proton and neutrons
the nucleus has a radius of…
1x10-14m
what is the relative mass of a proton?
1
what is the relative mass of neutrons?
1
what is the relative mass of electrons?
0
what is the charge of protons?
+1
what is the charge of neutrons?
0
what is the charge of electrons?
-1
what does the atomic number do?
tells you the number of protons
what does the mass number do?
tells you the total number of protons and neutrons in the atom
to get the number of neutrons…
subtract the atomic number from the mass number (top - bottom)
?—>2311Na
mass number
23?–>11Na
atomic number
What is an element?
- substance made up of atoms
- all have same number of protons in thier nucleus
what are isotopes?
- different forms of the same element
- same atomic number
- different mass numbers
how do you work out the relative atomic mass of an element?
sum of (isotope abundance x isotope mass number)
sum of abundance of all isotopes
what are compounds?
- formed from two or more elements
- elements react and atoms combine
a non-metal and metal compound
- consists of ions
- metal atoms lose electrons to form positive ions
- non-metal atoms gain electrons to form negative ions
- ionic bonding
what is ionic bonding?
- oppositely charged ions strongly attracted
- sodium chloride
- magnesium oxide
- calcium oxide
a non-metal compound
- consists of molecules
- each atom shares an electron with another atom
- covalent bonding
- hydrogen
- chloride gas
- carbon monoxide
- water
what is a mixture?
-no chemical bonds between elements, compounds
air is a mixture of gases
- nitrogen
- oxygen
- carbon dioxide
- argon
crude oil is a mixture of…
- different length
- hydrocarbon molecules
what are physical methods to seperate mixtures?
- filtration
- crystallisation
- simple distillation
- fractional distillation
- chromatography
chromatography - seperate dyes in and ink
- draw line near bottom of a sheet of filter paper (pencil insolube wont dissolve in solvent)
- add spot of ink to line and place sheet in beaker of solvent
- make sure ink isnt touching the solvent
- place lid ontop of beaker stop solvent evaporating
- solvent seeps up paper carrying ink
- different dye moves up at different rates seperating out forming spots
- insoluble dyes stay on baseline
- solvent reaches top of paper take out beaker and dry
- result is chromatogram
what methods can you use to seperate soluble solids from solutions?
- evaporation
- crystallisation
evaporation as a seperation technique?
- pour solution into evaporating dish
- slowly heat so solvent will evaporate, solution gets more concentrated
- keep heating until dry crystals are left
when can you not use evaporation?
-soluble solid doesnt decompose when heated
crystallisation as a seperation technique
- pour solution into evaporating dish and gently heat
- once some solvent has evaporated or crystals start to form remove dish from heat and leave to cool
- salt should start to form crystals as it becomes insoluble in cold, highly concentrated solutions
- filter crystals leave them in warm place to dry
what can you use to dry crystals in crystallisation?
- warming oven
- desiccator