Chemical Bonds Chapter Ionic Bonding 6.2 Covalent Bonding
Review of what you know An electron dot diagram is a model of an atom in which each dot represents a valence electron.
Notice dots for each family/group
Full energy levels When the outermost energy level of an atom is filled with electrons, the atom is stable and not likely to react. Nobel gases have stable electron configurations with eight valence electrons
Stable or not, Ions come!! Elements that do not have complete sets of valence electrons tend to react.
Ionic Bonding Some elements achieve stability through the transfer (give away) of electrons between atoms.
Ions Created View animation
Formation of Ions Ions are electrically-charged particles formed when atoms lose or gain electrons The charge on an ion is represented by a plus or a minus sign.
Cation – ion with a positive charge
Anion – ion with a negative charge
Did it Get or Give an Electron? Fe +3 Cu + Give
Did it Get or Give an Electron? Sn +2 Get Give Br -
Ionization Energy An electron can move to a higher energy level when an atom absorbs energy. The energy allows electrons to overcome the attraction of the protons in the nucleus. The amount of energy used to remove an electron is called ionization energy. It varies from element to element. The lower the ionization energy, the easier it is to remove an electron from an atom.
Remember Reactivity Demo?
Covalent Bonding A chemical bond in which two atoms share a pair of valence electrons. When two atoms share one pair of electrons, the bond is called a single bond
More Single Bonds
Double Bond shown in structural formula (not dots!)
What kind of bond?
Molecule A neutral group of atoms that are joined together by one or more covalent bonds.
Chemical Formula Used to describe the molecules of an element as well as a compound. The element hydrogen has the chemical formula H 2. The subscript 2 indicates that there are two atoms in a molecule of hydrogen.