The atomic number is always equal to the number of protons an element has.
Despite what we may think, so long as the chemical formula of a substance stays the same, a physical change has occurred. If H2O(s) changes to H2O(aq), it is only a phase change. However, if we break down H2O into it’s components, then there has been a chemical change.
Classifying equations- we’ve done a worksheet. Many students say they have trouble with double replacement and single replacement. Can you help them work on this?
Ionic- forms between ions, a metal and a nonmetal, steals electrons
Metallic- forms between metals when the positive nuclei of other atoms pull the valence electrons slightly out of their orbital shell; sea of valence electrons
Covalent- forms between nonmetals, bonds are shared. There are three- single, double and triple.
Single bonds- share one pair (two) of valence electrons
Double bonds- share two pairs (four) of valence electrons
Triple bonds- share three pairs (six) of valence electrons
Students must be able to tell whether NaCl is an ionic compound or a covalent compound
Nucleus- center of the atom, contains protons and neutrons
Protons- positively charged particles in the nucleus
Neutrons- neutral particles in the nucleus
Electrons- particles that orbit around the nucleus, “cloud of electrons”- 2)8)8)
Malleable- being able to be hammered and bent; associated with metals
The periodic table is laid out by atomic mass. As we move across the periodic table, reactivity falls- with the most reactive elements on the left side (alkali metals) and the least reactive elements on the right side (noble gases.)
Steps for writing ionic bonds:
Write down elements with charges
Remove charge sign
Steps for balancing equations:
Draw boxes around chemical formula ONLY (no coefficient)
Count # of atoms on each side
Place appropriate coefficient in front of boxes so that when multiplied (distributed,) atoms equal each other
Rewrite equation w/ correct coefficients
NO4: Ammonium Charge: +1
NO3: Nitrate Charge: -1
HCO3: BiCarbonate Charge-1
CO3: Carbonate Charge: -2
SO4: Sulfate Charge: -2
PO4: Phosphate Charge: -3
Nucleus of an atom only contains protons and neutrons. Therefore, the nucleus is positively charged.
Ions form when atoms become charged, either negatively or positively.