atomic bonding and the periodic table

Mixture

2 or more substances that are not chemically combined (elements or compounds) → separated by physical means, with no fixed composition and variable mp/bp

Compound

Require a chemical reaction to separate elements, has a fixed ratio of elements present, fixed mp/bp

Isotope

Atoms of the same element which have different number of neutrons but the same protons and electrons

Ions

Electrically charged particles formed when atoms lose or gain electrons

Separation example 1

Solvent+solute=solution

Separation example 2

Salt+water=evaporation/filtration/sieving

Separation example 3

Iron filings+sulfur=a magnet

Separation example 4

Ethanol+water=boiling+condensing tube

Atomic history

Democritus → found everything was made of particles surrounded by empty space

John dalton → elects had their own atoms that could not be divided or split

Jj Thompson → plum pudding model and found charges

Ernest Rutherford → alpha scattering experiment

Niehls Bohr→ electrons at set distances

James Chadwick → discovered the neutron, its mass and its charge

Column/ group

How many electrons in outer shell

Down/ period

How many electron shells

Atomic number

Number of protons

Atomic mass

Number of protons + number of neutrons

Dmititri Mendeleev

Created modern periodic by organising them into groups and periods of similar structure and increasing mass, leaving gaps for protected unfound elements based on properties

Element

Substances that only contain the same type of atom (same number of protons)

Atom

The smallest part of a chemical element that can exist

Electronic structure

Distribution of electrons of an atom or molecule in atomic or molecular orbits

Physical properties of metal (7)

Conductor (heat+electricity)

Malleable

High mp/bp

Sonorous

Ductile

High density

Shiny

Metal ion notes

Tend to have 3 or less outer electrons, so they give away their electrons to other atoms, becoming positively charged ions

Noble gases physical properties

Unreactive as full outer shell

Inflammable

Exist on their own

Non metals

Low densities

Group 8 trends

Going down:

Mp/bp increase

Density increase

Size increase

Alkali metals trends

Group 1:

Attempt to lose electron and become positively charged

Solid but soft at room temperature

Going down:

Reactivity increase

Density increase

Mp/bp decrease

Because number of electron shells increase so attraction weakens and bonds are easier to break

Equation 1

Metal + water (H²O) → hydrogen(g) [acidic] + metal hydroxide (OH) [alkaline]

alkali reactions examples (water)

Lithium: fizzes on top of water + produces hydrogen

Sodium: turns spherical + fuzzes diagonally + produces hydrogen

Potassium: burns with lilac flame + fizzes + produces hydrogen

Chlorine: flame + white smoke + solid form + colour fades

Halogen trends

Group 7 (non metals) going down:

Size of atom increase

Mass of atom increase

Density increase

Mp/bp increase

they are highly reactive so only used in small amounts and are diatomic molecules meaning they join with each other (Cl², Br², At²)

Transition metal notes

Similarities:

Conduct electricity in solid+liquid form

Shiny when first cut

Differences:

Higher mp/bp

Higher densities

Greater strength

Greater hardness

Compare transition metals and group 1

Group 1= reacts vigorously with cold water

Tm= reacts slowly, if at all

Group 1= reacts vigorously with halogens

Tm= same but not all also react

Group 1= reacts quickly with air

Tm= reacts slowly, if at all

Alpha scattering experiment

Rutherford passed positively charged alpha particles through gold foil. As some of them succeeded in passing through, he concluded the mass must’ve been concentrated in the centre of the atom. But as some were deflected he decided the atom’s nucleus was positively charged.

Isotope example

Monatomic

E.g. gold

Consisting of one atom/ exists on its own

Diatomic

E.g. hydrogen

Consisting of 2 atoms/ comes in pairs