Zusammenfassung der Ressource
Classification of Substances / Atomic Structure
- All substances are made up of atoms
- Elements are substances made up of only one type of atom
- Molecules are made up of two atoms chemically combined
- Hydrogen gas has chemical formula H2
- hydrogen atoms not stable on their own
- pair up into molecules
- Oxygen
- O2
- Nitrogen
- N2
- Chlorine
- Cl2
- Compounds are made of two or more elements chemically combined
- formed when atoms/molecules react with each other in order to become more stable
- Mixtures contain two or more different substances mingled together but not chemically combined
- easily separated
- air
- mixture if gasses
- sea water
- water and salts
- alloys
- mixture of metals
- The properties of a compound differ from those of the elements from which it is made
- Atomic Structure
- The Atom
- The atom is the smallest part of an element ehich can take part in a chemical reaction
- sub-atomic particles
- protons
- +1 charge
- in the nucleus
- 1 AMU
- neutrons
- 0 charge
- in the nucleus
- 1 AMU
- electrons
- -1 charge
- orbiting the nucleus
- 0 AMU
- Atomic Numbers and Mass Number
- Atomic number is the number of protons (or electrons) in an atom of an electron
- Number of protons = Number of electrons
- Mass number is the number of protons and neutrons in an atom of an element
- arrangement of electrons is called electronic configuration
- The Bohr Structure
- Electrons represented in dots
- The first shell holds two electrons and the rest hold up to eight
- Isotopes
- Isotopes are atoms of the same element which have the same atomic number but different mass numbers
- same number of protons, different number of neutrons