Atomic Structure & The Periodic Table Flashcards
Non metal elements that exist as molecules, two atoms together
Iodine, bromine, chlorine, fluorine, oxygen, nitrogen, hydrogen
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Mixture
Two or more elements or compounds not chemically combined together
-chemical properties are the same
Ways to separate mixtures (5)
-filtration
-crystallisation
-simple and fractional distillation
-chromatography
These are physical processes, do not involve chemical reactions and no new substances are made
Compound
A substance that contains two or more elements that are chemically combined
-elements in compounds always have fixed proportions e.g. CO2= 12g of carbon 32g of oxygen
Ion
A charged particle formed when an atom or group of atom loses or gains electrons
e.g. sodium=Na+, one positive electrical charge
Ionic compound
When a negative ion (atom that has gained an electron) joins with a positive ion (that has lost an electron)
State symbols
Symbol in chemical equations to show if a substance is solid,liquid, gas or an aqueous solution
A pure substance consists of …
Only one element or compound
Filtration
When a mixture is separated through using filter paper and a funnel and pouring the mixture through the paper and funnel so the liquid drips through and the solid remains in the paper.
Crystallisation
When a solution is placed over a Bunsen burner in an evaporating basin and heated which causes the water in the solution to evaporate and leave the solid crystals behind
Simple distillation
When the dissolved solute has a much higher boiling point than the solvent in a solution so when it is heated the solvent evaporates
Fractional distillation example with water and ethanol
- water and ethanol solution heated
- ethanol evaporates first, travels up through the fractioning column and is cooled, condenses and is collected in a beaker
Paper chromatography
- water and ethanol solution heated
- paper with pencil line on and ink or plant dye lowered into it
- the dye spreads up the paper
Uses for paper chromatography
-distinguishes the difference between pure and impure substances by the amount of spots on the paper they produce
John Dalton 1803
Thought all matter was made of tiny particles called atoms
-thought they were tiny spheres that could not divide
JJ Thomson
- discovered the electron
- created the plum pudding model we’re the atom is a ball of positive charge with negative electrons embedded in like currants in a cake
Ernest Rutherford 1909
- Created the nuclear model, mass is concentrated at the centre (the nucleus)
- this nucleus is positively charged
Alpha particles
Subatomic particles comprising of 2 protons and neutrons, the same as a helium nucleus
Niels Bohr
- discovered electrons orbit the nucleus in shells a certain distance away
- discovered the nucleus contained protons which had a positive charge
James Chadwick 1932
- discovered neutrons
- developed the model we use today
Neutrons
Subatomic particles with no charge but a mass of 1
Protons relative mass and charge
1
+1
Neutrons relative mass and charge
1
0
Electrons relative mass and charge
Basically 0
-1
Atomic number
Number of protons in the nucleus of an atom
Atoms of a given element have —— number of protons
The same
An atom contains equal numbers of…
Protons and electrons
-results in atoms having no overall charge
Mass number
Number of protons and neutrons in the nucleus of an atom
Isotopes
Atoms of an element with different numbers of neutrons
-these atoms have the same atomic number but different mass numbers as atoms of the same element
How many isotopes of hydrogen are there
3
Relative atomic mass
The mean relative mass of the atoms of the different isotopes of an element
Dmitri Mendeleev
- created the first periodic table in 1869
- arranged it by atomic weight
- had gaps in it
Periods (periodic table)
Were elements are arranged in rows in order of increasing atomic number
Groups
Were elements with similar properties are placed in vertical columns
Electronic structure
The way in which electrons are arranged in an atom
Number of shells links to…
Period number
Number of electrons on outermost shell links too…
Group number
The numbers added together (e.g. 2+8+1=11) links to…
Atomic number
Metals
Shiny, good conductors of electricity and heat and form basic oxides
- loose electrons to form positive ions
Non-metals
Poor conductors, form acidic oxides , dull
Were are metals and non-metals on the periodic table
Metals = left
Non-metals =right
Reaction of metals and non metals
Metals = loose electrons and form positive ions Non-metals = gain electrons and form negative ions
Noble gases
Elements in group 0
- low boiling points ( become higher as you go down the group)
- very unreactive, have full outer shells so are stable
Alkali metals on the periodic table
Group 1 elements -soft -low melting points (becomes lower as you go down the group) -low densities Reactivity increases down the group
Lithium reaction in water
Fizzing, becomes smaller and dissolves
Sodium reaction in water
Fizzes rapidly
Forms a ball
Dissolves
Potassium reaction in water
Burns violently, sparks
Lilac flame
Forms a ball
Disappears rapidly, often with small explosion
Alkali metals reaction with oxygen
- burns vigorously
- forms a white smoke
- forms white oxide on the surface of the metal
Halogens
Group 7 elements, produce salts when reacted with metals
Relative molecular mass, Melting and boiling point increases down the group
Reactivity decreases down the group
Covalent bonds
A bond between atoms formed when atoms share electrons to achieve full outer shells
Halogens reaction with metals
Produce salts, held together by ionic bonds
Halogens reaction with non metals
With hydrogen, produces a compound called hydrogen halide which are gases at room temp, dissolve in water and produce acidic solutions
In a reaction, a more reactive halogen can…
Displace the less reactive halogen in a displacement reaction
