1.1 Model of the Atom Flashcards
What do chemical symbols represent? e.g. Na and O
An atom of an element
Na- represents atoms of sodium
O- represents atoms of oxygen
How are compounds formed?
From elements by chemical reactions
What do chemical reactions involve?
- Formation of one or more new substances
- Often a change in energy
What is a compound? Give an example
Two or more elememts that are chemically combined in fixed proportions
HCl
NaCl
How are compounds separated back into elements?
Only by chemical reactions
What is a mixture?
Two or more elements or compounds not chemically combined
What is the difference between a compound and a mixture?
Compound
- Two or more elements chemically combined
- Only separated by a chemical reaction
Mixture
- Two or more elements or compounds not chemically combined
- Can be separated by physical processes
How can a mixture be separated?
Filtration
Crystallisation
Simple distillation
Fractional distillation
Chromatography
What is the plum pudding model of the atom?
Atom is a ball of positive charge with electrons in it
What experiment proved the plum pudding model was incorrect?
Alpha particle scattering experiement
What was done in the alpha particle experiment?
- Beam of alpha particles aimed at thin gold foil
- Some particles detected at different angles and some came back straight
- Alpha particles were being repelled and deflected by positively charged nucleus
What is an alpha particle?
2 protons and 2 neutron nucleus
Therefore He2+
Fill in the table
What is the charge of an atom?
0
Number of protons is equal to number of electrons
Fill out the table