Atomic Structure And The Perodic Table Flashcards
Periodic table
All elements in a group have similar chemical properties
This is because all the elements in a group have the same number of electrons in their outer shell
In an element are all the atoms the Same
Yes
Compound
Compounds contain two or more different elements chemically combined in a fixed proportion
Do compounds usually have the same properties to the elements that they are made from
No they usually have totally different properties
How do you separate a compound to get back the original elements
With a chemical reaction
Mixture
In a mixture, we have different elements or compounds not chemically combined together
How can you separate a mixture
Physical techniques e.g. Filtration, crystallisation
Molecules
Has any elements chemically joined
What does the little number mean next to an element symbol e.g. O(4)
That there are multiples of that element e.g. O(4) = 4 oxygens
Specific compound
The number of atoms of each element is fixed
Name 4 physical separation techniques
Filtration
Crystallisation
Distillation
Chromatography
What is a Physical separation technique
Used to separate mixtures
Can’t be used to separate elements in a compound
Filtration
Used to separate an insoluble solid from a liquid
Crystallisation
Used to separate a soluble solid from a liquid
Simple distillation
Used to separate a liquid from a solid if we want to keep the liquid
Fractional distillation
Allows us to separate two different liquids
The 2 liquids must have different boiling points
How does simple distillation work
1) evaporate the liquid by heating
2) condense the vapour by cooling
Atomic number
Bottom number
=proton number
Mass number
Top number
Neutron number = mass number - atomic number
Isotope
Atoms of an element with different numbers of neutrons
Relative atomic mass
The average of the mass number of the isotopes
Equation for relative formula mass Ar
(Mass isotope 1 x % isotope 1) + (mass isotope 2 x % isotope 2)
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100
What Mendeleev do to the elements of the periodic table
Arranged elements in order of atomic mass
Wha did Mendeleev predict
He predicted the properties of the undiscovered elements based on other elements in the same group
When the elements were discovered the properties were found to almost exactly what he had predicted
Transition metals
Less reactive
Highly reactive metals
Group 1&2
Ions
Charged atom
Metals form positive or negative ions
Always positive
Group 0 noble gases
Very unreactive
Full outer shell
Boiling point group 0
Increase going down the group
Group 1 alkali metals
Very reactive
1 electron on outer shell
Reacts with oxygen, water and chlorine rapidly
Reactivity group 1
More reactive going down the group
Group 7 the halogens
Form molecules with 2 atoms joined by a covalent bond
Non metals
Boiling point group 7
Increase as we move down the group
What is the negative electron attracted to
The positive charge of the nucleus
Reactivity group 7
Less reactive going down the group
