C2 Flashcards
What was the first atom theory?
-In ancient Greece people thought that there were 4 basic elements. 2 people thought that there must be something smaller that made up these elements that could not be broken up-The atom
What did John Dalton believe?
He described atoms as solid spheres that made up chemical elements we know today.
Why did JJ Thompson think that atoms weren’t solid spheres?
His experients led him to believe that atoms contain electrons. He came up with the ‘plum pudding model’
The plum pudding model stated that atoms wre positively charged with electrons stuck on to it
How did Rutherford show that the plum pudding model was wrong?
He fired positively charged alpha particles at an extremely thin sheet of gold.
From the plum pudding model they expecting all to pass straight through as the positive charge of the atom was thought to be very spread out
Instead lots more particles were deflected than expected
Rutherford came up with the idea that atoms contained a nucleus, which was positively charged and the nucleus was surrounded by electrons
What is Bohr’s theory?
Bohr proposed that electrons orbit the nucleus in fixed shells
What is the atom made up of?
Protons+
Electrons-
Neutrons
What is the nucleus made up of?
The nucleus is located in the center of the atom
- contains Protons and Neutrons
- contains almost the whole mass of the atom
- extremely tiny compared to size of the atom
What are electrons?
Negatively charged particles
- orbit round the nucleus in shells
- virtually no mass
What is the mass number of an atom?
The total numbeer of protons and neutrons
What is the atomic number?
The total number of protons an atom has
-Determines the element
What are ions?
Atoms which have lost or gained electrons
- negative ions form when atoms have gained electrons
- positive ions form when atoms have lost electrons
What are isotopes?
Isotopes are different forms of the same element, which contain the same number of protons but different numbers of neutrons.
What was Dmitri Mendeleev’s periodic table ?
He put the elements in order of atomic mass
-He left many gaps for undiscovered elements, allowing Mendeleev to predict what their properties would be, which would help confirm Mendeleev’s theory.
What are the rules for an electron shell?
1st shell-2 electrons
2nd shell-8 electrons
3rd shell-8 electrons
How does the electronic structure of atoms affect how they will react?
Metals which don’t have many electrons to lose on their outer shell can lose their electrons very easily, as the electrons have a weak attraction to the nucleus
For non-metals, forming ions is more difficult as there are either lots of electrons to remove, or the electrons have a strong connection to the nucleus.
What are the properties of metals?
- Shiny appearance
- Good conductors
- High densities
- High boiling and melting points
- Re activity increases as you go down the periodic table
What are the properties of non-metals?
- Dull looking
- Poor conductors
- Low densities
- Usually gases or liquids at room temperature
- Reactivity decreases down the periodic table
What are the properties of transition metals?
- can form more than 1 ion
- high melting points
- less reactive than group 1 metals
What are the properties and patterns of group 1 elements?
- Very reactive as they only have to lose 1 electron
- Melting and boiling points decrease as you go down the group
- Reactivity increases as you go down the group; electrons become further and further away
- Decrease in hardness as you go down the group
- Increase in R.A.M and density as you go down the table.
What does aqueous mean?
Dissolved in water
How do group 1 metals react?
They all react to form the same product, but become more vigorous as you move down the table
All group 1 metals tarnish in moist air-have to be kept in oil to prevent reaction with air
What are the properties of group 7 elements?
7 electrons in their outer shell
Exist as diatomic molecules
-share 1 pair of electrons in a covalent bond gives them a full outer shell. e.g. Br2
As you go down the group, reactivity decreases as elctrons become closer to the nucleus
What happens in a displacement with halogens?
chlorine + potassium bromide –> Potassium chloride + bromine
A more reactive halogen (chlorine) will displace a less reactive halogen (bromine).
What are the properties and patterns of the noble gases?
- All have 8 electrons in their outershell-unreactive
- Monatomic gases-single atoms not bonded
- Colorless gases at room temperature
- Melting and boiling points increase as you go down the table
What is ionic bonding
The transfer of electrons
- can form a positive ion (cation)
- can form a negative ion(anion)
What are ionic compounds?
Giant ionic lattice structures
-strong forces of attraction between oppositely charged ions
What are the properties of ionic compounds?
-High melting and boiling points because of strong forces of attractions
-Do not conduct because particles are in a fixed place and do not move
Many can dissolve easily in water.
