Presentation on theme: "Chemical Bonding Joining atoms together to make compounds."— Presentation transcript:
Chemical Bonding Joining atoms together to make compounds
Chemical Bonding: combining atoms of elements together to form new substances Bond: force that holds atoms together to form molecules
Molecules Two or more atoms that form a new substance Smallest part of a compound
Review of atomic structure Atoms: electrons, protons, neutrons Electrons are negatively charged Protons are positively charged Neutrons have no charge Electrons are in energy levels First level = 2 electrons Second level = 8 maximum electrons Third level = 18 maximum electrons
Valence electrons: the outermost electrons Determine how and with what the atom will bond Electrons and energy levels video Electrons and energy levels video Electrons and energy levels video
FACT: Atoms become stable (won’t react chemically) when they have a full outer energy level.
Bohr model review Bohr model review Start with a circle (nucleus) Put in proper number of protons (atomic number) Calculate number of neutrons Atomic mass – mass of protons = neutrons Place electrons: Start in inner ring, fill first then move to next Start at “12:00”, then “3”, then “6”, then “9” Once shell is half full, electrons pair up
Electron Dot Diagrams Electron dot diagrams used to show how many valence electrons are in an element Rules: 1.Start with the symbol for the element –Represents nucleus and “inner” energy levels 2.Count how many valence electrons are in the outer shell 3.Place one dot at a time working around the symbol, usually start at “3:00” position o- -
Octet Rule: Fill the outer shell to give a total of 8 shared electrons Makes a stable molecule, will not react further
Types of Bonds Ionic Bonds: transfer of electrons from one atom to another Ions: Positively or negatively charged atoms Since negatives and positives attract, the atoms bond to each other Usually happens between a metal and a nonmetal Ionic Bonding video Ionic Bonding video Ionic Bonding video
Which elements do you think will bond together?
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Covalent bonding: Sharing electrons equally between two or more atoms Example: Hydrogen has one valence electron so it needs one more to fill up its energy level Covalent bonds often happen between like elements Usually happens in non-metals Cl 2, H 2, O 2 Covalent Bonds Covalent Bonds video