Chemistry:Atoms and Molecules Notes

Definitions

Atom - The smallest unit of matter that can exist of an element. Compound - A molecule containing two or more different atoms bound together. Element - A fundamental substance that has a unique atomic number on the periodic table. Isotope - A different form of an element that varies by the number of neutrons in the nucleus.Neutron - An uncharged atomic particle of mass 1.67493x10-27 . It resides in the nucleus. Nucleus - The small, dense central region of an atom around which electrons orbit. The nucleus is made up of protons and neutrons.Proton - A positively charged particle of mass 1.6726x10-27 . Protons reside in the nucleus.Valence electrons - The electrons in the outermost energy shell of an atom. The configuration of these electrons determine the chemical properties of the element. Valence shell - The highest energy shell in an atom, containing valence electrons. All interactions between atoms take place through the electrons of the valence shell.

Protons, Electrons and Neutrons[Subatomic particles]

ProtonsCharge: +1Mass: 1ElectronsCharge: -1Mass: 1/1840NeutronsCharge: 0Mass: 1

Atoms

1)Definition:Atom - The smallest unit of matter that can exist of an element.2)Chemical Symbol:X-AA:Nucleon numberX:Symbol of elementProtons=ElectronsNucleon:Protons+Neutrons

Molecules

1)Definition: Molecule-A group of 2 or more atoms chemically combined together

Difference between Atom and Molecule

Atoms: Like LegoMolecule: Things that we make using Lego blocks

Ions

1)Definition: A group of atoms or an atom with electrical charge.2)Neutral: No charge3)Cation: Positive ion---CATion PAWSitive4)Anion:Negative ion---A Negative Ion5)Polyatomic ion:A group of atoms that have a chargeMetals Lose electrons Form positive ions Non metalsGain electronsForm negative ions

Isotopes

1)Definition: Different versions of a certain kind of atom

The Periodic Table

Groups:ColumnsPeriods:Rows**For groups,must write in Roman numeralsGroup 7-Ide for metal-non metals

Extra Notes