Atoms © by Dr H - W Winter Blue slides: just read and enjoy Yellow slides: copy into your book

Atomic Theory An ATOM is a very small building block of matter. Atoms are so small that we cannot see them, not even with the best microscopes in the world. Many atoms together can be seen.

All known matter is made up of atoms. A teaspoon full of sulfur (5g) contains about or atoms. There are over 100 different types of atoms, each type is called a chemical element.

Atoms can now be “seen” through special technology Image of individual atoms in Mica (from Digital Instruments)

To get an idea of “the size od an atom” click in the hyperlink:

The Carbon Atom proton The Hydrogen Atom More than 100 Different Types of Atoms

Protons (+ electric charge), p Electrons (– electric charge), e Neutrons (no charge), n Proton and Neutron have about the same mass Electron is about 2000 times less massive than proton Electrical Forces produce attraction between electrons and the protons in the nucleus (they are oppositely charged) Atoms are made from sub-atomic particles

Table of Sub-atomic Particles n0n0 nucleus01neutron e-e- electron shell -electron p+p+ nucleus+1proton SymbolWhere found Charge of particle Mass in mass units Name

Atoms are called a certain chemical element if they all have the same number of protons in their nucleus. Hydrogen: 1 proton & 1 electron proton The electron orbits the proton in an ”electron shell” at more than half the speed of light (like satellites around Earth).

The Carbon Atom The nucleus is made up by 6 protons 6 neutrons and 2 in the 1 st shell 4 in the 2 nd shell 6 electrons are found in the electron shells: Most of the atom is empty space The nucleus is the heaviest part of the atom

The first 20 elements of the Periodic Table NoSymbolNameHelp 1HHydrogenHarry 2HeHeliumHe 3LiLithiumLikes 4BeBerylliumBeer 5BBoronBy 6CCarbonCupsfull 7NNitrogenNot 8OOxygenOver 9FFluorineFrothy 10NeNeonNelly’s NoSymbolNameHelp 11NaSodiumNaughty 12MgMagnesiumMG 13AlAluminiumAlways 14SiSiliconSits 15PPhosphorusParked 16SSulfurSo 17ClChlorineCleverly 18ArArgonAround 19KPotassiumK-Road 20CaCalciumCarpark

Types of Particles Molecules 2 or more atoms permanently connected to each other (bonded) through their electrons i.e. H or hydrogen atomH 2 or hydrogen molecule H 2 O or Water molecule Atoms

Types of Particles Ions An atom or a group of atoms that have gained or lost electrons. Cl - or chloride ion Na + or sodium ion SO 4 2- or sulfate ion OH - or hydroxide ion

Types of Matter An Elementis a pure substance made up of only one type of atoms. An element can be made of single atoms (i.e. Helium He) An element can be made of molecules (i.e. Nitrogen N 2 )

A compound can be made of two types of atoms, oxygen and hydrogen Types of Matter A Compoundis a molecule made up of two or more types of atoms. (i.e. Water H 2 O) O H

Types of Matter Pure SubstanceA material made up of only one type of particles. H 2 hydrogen molecules H 2 O water molecules He Helium atoms

Types of Matter MixtureSeveral different particles blended together. Air: 78% N 2 21% O 2 1% Ar 0.04% CO 2 Salt Water: H 2 O Cl - (chloride ions) Na + (sodium ions) - +