Presentation on theme: "The Ancient Greeks used to believe that everything was made up of very small particles. I did some experiments in 1808 that proved this and called these."— Presentation transcript:
The Ancient Greeks used to believe that everything was made up of very small particles. I did some experiments in 1808 that proved this and called these particles ATOMS: Dalton
Elements are substances that consist of just one type of atom- they cannot be broken down to other substances The basic unit of all matter is the atom, the smallest unit of matter that retains the properties of an element A Molecule is a substance containing 2 or more atoms A Compound is a substance containing 2 or more elements
Is brass an element? What about: Oxygen O 2 Water H 2 0 Helium He Is brass a molecule? Is brass a compound?
The structure of the atom ELECTRON – negative, orbits outside the nucleus PROTON – positive, also in nucleus NEUTRON – neutral, located in the NUCLEUS (center of atom)
The Atom Hydrogen Proton Electron Hydrogen has one proton, one electron and NO neutrons
The Atom Helium Electron Proton Neutron Helium has two electrons, two protons and two neutrons
The Atom Carbon Protons Neutrons Electrons Carbon has six electrons, six protons and six neutrons.
The Atom Nitrogen Protons Neutrons Electrons Nitrogen has seven electrons, seven protons and seven neutrons.
The Atom Oxygen Protons Neutrons Electrons Oxygen has eight electrons, eight protons and eight neutrons.
Hydrogen atoms are very reactive…. Helium is not. Which do you think the Hindenburg was filled with? Atoms want 8 electrons in the outermost shell. If atoms have less than 8 then they react with other atoms to gain or lose electrons.
There are an estimated 10 40 possible compounds containing up to 50 atoms The known chemical world, including natural and synthetic compounds, is far far far below 1% of that. N ATURE volume 442 p. 502 3 August 2006
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