Atomic Structure And The Periodic Table Flashcards
What is chromatography?
Chromatography is the separation of soluble substances
How does it work? - CHROMATOGRAPHY
Your soluble mixtures will be on paper at a level line. The paper is lowered into a solvent, and some dyes spreads up the paper, at different rates.
Why do the mixtures move? - CHROMATOGRAPHY
The different parts of mixtures are attracted to either the paper or the solvent, meaning the mixture separates
How many spots do pure/impure substances make? - CHROMATOGRAPHY
A pure substance creates 1 spot
An impure substance creates more than 1 spot
What were John Dalton’s ideas about atoms? - S+B
That they were tiny, indivisible spheres
Who discovered the electron and what model did this create? - S+B
JJ Thomson, who created the plum pudding model
1909
What experiment did Ernest Rutherford create and what did he find? - S+B
He fired positive alpha particles at gold foil. Most went straight through but some were deflected. This led him to suggest the nuclear model
What is the nuclear model? - S+B
An atom, with its mass concentrated at the positively charged nucleus
Who discovered the electron? - S+B
JJ Thompson
Who discovered neutrons? - S+B
James Chadwick - 1932
What is the atomic number? S+B
The number of protons in an element
What is the mass number of an element? - S+B
The mass number is the number of protons + neutrons in an element
What is an isotope? - S+B
An atom with the same number of protons but a different number of neutrons
What is the symbol for relative atomic mass? - PT
Ar
What problems did John Newlands’ periodic table have? - PT
He didn’t order elements in terms of atomic weight, put multiple elements in the same place, changed positions of elements.
What was good about Mendeleev’s table? - PT
It had spaces left for predicted new elements, decided where elements where misplaced, had elements with similar properties in groups.
Name 4 properties of metals - S+B
Good electric conductors, high melting points, very dense, strong, shiny, ductile
Name 4 properties of non metals - S+B
Low melting point, low density, weak, not ductile, not malleable, poor conductor of electricity
What is Group 0 of the periodic table? + name to properties - PT
The noble gases
Single atoms, very low boiling points, VERY UNREACTIVE
What is group 1 of the PT? + name 2 properties - PT
Alkaline metals
Fairly low melting points
Low densities
Soft (can be cut by a knife)
What happens when Lithium reacts with water? - Reactions
Fizzes slowly
What happens when potassium reacts with water? - Reactions
Burns violently with a lilac flame, often explodes
What do halogens exist as? - S+B
Molecules (diatomic)
What happens to the melting and boiling points of group 7 element as you go down the group? - S+B
It’s boiling point and melting point increase.
Larger molecules, mean stronger intermolecular forces, requiring more energy to break
What can more reactive halogens do to less reactive halogens in a solution? - S+B
More reactive halogens can replace less reactive halogens
Does halogen reactivity increase up or down the group? - PT
Up
Name 4 properties of transition metals - S+B
Can conduct electricity when solid and liquid, shiny when first cut, high densities, high melting points, strong, hard
What can transition metals do in terms of ions? - S+B
They can form ions with different charges
What is the symbol for relative molecular mass?
Mr
What did John Newlands (1864) discover?
Law of octaves-
Arranged elements by atomic weight and found the elements eight apart had similar properties
What was the flaw with Newlands theories?
Didn’t consider some elements may be undiscovered and so some elements were grouped with elements of different properties.
What did Mendeleev do?
Realised that an elements mass was related to its physical and chemical properties. Arranged the elements vertically into groups of similar properties.
He left spaces where undiscovered elements would be
Which elements did Mendeleev switch around and why?
Iodine and tellurium.
With Mendeleev’s theory, iodine should have been before tellurium but to match up iodine’s properties with chlorine and bromine, he switched them round.
What did Henry Moseley (1913) do?
Suggested that periodic table should be organised by atomic number not atomic weight (this supported Mendeleev’s decision to put iodine after tellurium)
Where in an atom are protons found?
Found in the nucleus
Where in an atom are neutrons found?
In the nucleus
Where in an atom are electrons found?
On the outside of the atom in electron “shells”
What is atomic mass?
Number of protons + number of neutrons
What is the atomic number?
The number of protons (-same as the number of electrons)
What does the word element refer to?
A substance made up of only one type of atom
What does the word compound refer to?
A substance made of more than one type of atom- chemically joined
When an atom becomes an ion, what happens?
It becomes charged by losing/gaining electron(s)
What charge would an ion be if it lost electron(s)
Positive
What charge would an ion be if it gained electron(s)
Negative
What is the word ending for a negative ion?
-ide
What type of atoms does ionic bonding occur between?
Metal + non-metal
What does ionic bonding involve?
Electrons are TRANSFERRED (moved) between atoms to form charged ions.
What type of structure is formed through ionic bonding and why?
(Giant) lattice. Oppositely charged ions that are formed attract each other (ELECTROSTATIC attraction).
Name four properties of ionic bonding
- High MPt/ BPt
- dissolve in water
- conduct electricity when molten/ dissolved
- very strong
What type of atoms does covalent bonding occur between?
non-metals
What does covalent bonding involve?
Electrons are shared
Describe simple covalent molecules?
- the MOLECULES have strong covalent bonds within them
- however, there are weak INTERMOLECULAR forces between molecules (low MPt/ BPt and gas at room temperature)
Give an example of giant covalent substances
Graphite, diamond, silicon dioxide
What type of atoms does metallic bonding occur between?
One or more metal atoms
What does metallic bonding have that other types of bonding do not?
Delocalised electrons
What do delocalised electrons do?
They hold together positive metal ions, carry charge and carry heat.
Name properties of metallic bonding
Thermal conductor, electrical conductor, high MPt/ BPt
What is an alloy?
A mixture of two or more elements where one is metal.
Which properties can change when alloys are formed?
- MPt and BPt
- hardness
- likelihood to rust
