topic 1 - atomic structure and period table Flashcards
about the nucleus
- contains protons and neutrons
- psotivite charge bc of protons
relative mass and charge of a proton
relative mass: 1
charge: +1
relative mass and charge of a neutron
relative mass: 1
charge: 0
relative mass and charge of a electron
relative mass: 0
charge: -1
what does the mass number tell you and where is it
- above the letters - top number
- tells you total number of protons and neutrons
what does the atomic number tell you and where is it
- below the letters - bottom number
- how many protons there are
how do you get the number of neutrons
mass number - atomic number
whats an isotope
- different forms of the same element
- same number of protons / different number of neutrons
whats a compound
- formed from 2 or more elements reacting together and becoming chemically bonded
whats a mixture and examples
- 2 or more substances not chemically bonded
- air
- crude oil
3 separation techniques
- filtration
- evaporation
- crystallisation
simple distillation
separating liquid from a solution if they have very DIFFERENT boiling points
- solution heated
- the part with lowest boiling point evaporates first
- vapour cooled and condensed in tube into flask
fractional distillation
separating liquid from a solution if they have very SIMILAR boiling points
- fractional column
- lowest boiling point evaporates first
- once these are collected you raise the temperature until the next one reaches the top
order of history of the atom
- John Dalton
- jj Thompson
- Ernest Rutherford
- niels bohr
- janes chadwick
what did john dalton discover
- atoms were solid spheres that made up different elements
what did jj thompson discover
PLUM PUDDING
- Dalton was wrong and atoms weren’t solid spheres
- atoms were ball of positive charge with negative electrons stuck in it
what did rutherford discover
- due to plum puding model they thought that firing positive alpha particles through gold sheet they would j pass through BUT…
- some passed through and some deflected back and therfore plum pudding couldnt be right
- new evidence - NUCLEAR MODEL
- positive nucleus in the centre with concentrated mass with a cloud of negative electrons surrounding this nucleus so most of atom is empty space
what is bohr discover
- electrons orbit the nucleus in fixed shells
what did Chadwick discover
- neutrons in the nucleus
numbers in shell rule
2:8:8
how was the periodic table organised in the 1800s
- physical and chemical properties
- atomic wieght
why did Mendeleev leave gaps in the periodic table
- to make sure that elements with similar properties stayed in the same groups because not everything had been discovered yet
properties of metals
- METALS form positive ions when they react
- metallic bonding
- strong
- conduct heat and electricity
- high melting and boiling points
properties of non metals
- form negative ions when they react
- dull
- brittle
- dont conduct electricity
