Module 2.1

Fitfth century BCE (before the common eraa) -The greek atom -thought atoms would be indivisible .

A Early 1800S - Dalton’s atomic theory : He stated : -Atoms are tiny particles that make up elements. -All aotms of a given elemnt are the same . -Atoms of one element re different form those of every other element . -Developed the first stable of atomic msses .

(1897-1906) J.J Thompson - electron discovery . He discovered that cathode rays were a stream of partiles with the following properties . -Had negative charge . -Could be deflected by both magnet + electric field . -Very very small mass . -Concluded electrons came form the atoms of the electrpdes themselves . (DALTON DISAPPROVED).

(1909-1911) Ernest Rutherfords gold-leaf experiment . alpha particles were filed at a thin sheet of gold foil , the results were . -Most paricles were not deflected t all . -However a small percentage were deflected by the source . -Some deflected bck towards the source .

-Positively charge of an atom + most of its mass re cocentrated t the center (the nucleus ) . -Negative electrons orbit the nucleus . -Most of an atom’s vpolume would be the space between the tiny nucleus + negative electrons . -So positive charge = negative charge .

-Bohr altered Rutherford’s model to allow electron to only follow certain paths . Or they would spiral into the nucleus periodic properties Bohr;s model helped to explain . -Spectracal lines seen in emission spectrum . -The energy of electrons at different distances from the nucleus

discovered a link between x-raus freqiemcoes amd am elment’s atomic number . Rutherford’s discovery of the proton was thena ble to explain Moseley;s findings that an atom;s atomic number was linked to x-ray frequencies . WWe know atomic number = protons .

He observed a type of radiation made up of uncharged particles with apporximately the same mass as a portien now called neutron .

-1923-26 in 1923 the frnech physicist called Lous de Broglie suggesgted that prticles could hve the nature of both a wave and qne q pqerticle . -In 1926 the austrain phsycis erwin chrodinger suggest that an electron had wave-like properties ina na tom . He also introduced the idea of atomic orbitals .

Modern day -It is now thought that protons and neutrons themselves are made up of even smaller particls called quakrs . Our understaning of the aom is likely to progress and sceince andvances further and further .

This is because -Chemical reactions involve electrons , and isotopes have the same number nd arrangement of electrons . -Neutrons make no difference to chemical reactivityy .

HCL –> Hydrochloric acid nitric acid sulfuric acid ethanoic acid -Key is that all acids contain the element hydorgen .

-The hydrogen ion is simply a proton -CHECK THE SHEET - Scientists say that the acid molecule dissociates - splits -when this happens, it also produces a negative ion (chloride ion in the case of HCL ).

HCL IS A strong acid . -sulfuric + ntiric acid are also strong acids .

-in the case of ethanoic acid , only a small percentage of the acid molecules dissociate. Therefore as it only partially dissociates it is a weak acid.

metal hydroxides , metal carbonates, and ammonia.

it can neutalise an acid to porduce a salt .

• when we form the salt , the metal ion in the metal oxide has replaced the hdyrogen ions in the acid . -In this case ,t he copper ion from the copper oxide has sreplaced the hydrogen ions int he sulfuric acid to form the salt + copper sulfate.

-Can also see the oxide has formed formt he oxide from the copper oxide and hydrogen ions have formed water.

… -cabornate + acid —> salt + water + carbondixoide .

-both of these re bases, as they neutralise aicds, producing salt. -copper oxide is insoluble in acid, so is a base only.

sodium hydoricide solution is an alkali

need to learn this .

-Ammonia is a gas that is highly soluble in water , producing the alkali ammonia hydroxide .