Chemistry
(future Periodic Table of Elements)
The Periodic Table is made up of periods and groups of elements.
A period consists of the elements in any one horizontal row of the periodic table. A group consists of the elements in any one column of the periodic table.
Here are just a few:
Neon ------- Ne
Zinc -------- Zn
Silver ------ Ag
Magnesium -- Mg
Calcium --- Ca
Lead ------- Pb
Mercury --- Hg
Tin ---------- Sn
A proton is a nuclear particle having a positive charge equal to that of the electron and a mass more than 1800 times that of the electron.
A neutron is a nuclear particle having a mass almost identical to that of the proton but with no electric charge.
The atomic number (Z) is the number of protons in the nucleus of an atom.
The mass number (A) is the total number of protons and neutrons in a nucleus.
Isotopes are atoms whose nuclei have the same atomic number but different mass numbers; the nuclei have the same number of protons but different number of neutrons.
Rules for naming binary molecular compounds using the prefix system:
1) The name of the compound has the elements in the order given in the formula.
2) You name the first element using the exact element name.
3) You name the second element by writing the stem name of the element with the suffix -ide.
4) You add a prefix to each element name to denote the subscript of the element in the formula.
Consider N2O3. This is a binary molecular compound so because N and O are nonmetals, according to Rule 1, you name it after the elements N before O, following the order of elements in the formula. By Rule 2, the N is named exactly as the element (nitrogen), and by Rule 3, the O is named as the anion (oxide). The compound is a nitrogen oxide. Finally, you add prefixes to denote the subscripts in the formula (Rule 4). As the table shows, the prefix for two is di-, and the prefix for three is tri-. The name of the compound is dinitrogen trioxide.
A chemical equation is the symbolic representation of a chemical reaction in terms of chemical formulas. For example, the burning of sodium in chlorine to produce sodium chloride is written:
2Na + Cl2 ------> 2NaCl
The formulas on the left side of an equation (before the arrow) represent the reactants; a reactant is a starting substance in a chemical reaction. The arrow means "react to form" or "yield". The formulas on the right side represent the products; a product is a substance that results from a reaction. Note the coefficient of 2 in front of the formula NaCl. Coefficients such as this give the relative number of molelcules or formula units involved in the reaction. Coefficents of 1 are usually understood, not written. In many cases, it is useful to indicate the states or phases of the substances in an equation. You do this by placing appropriate labels indicating the phases within parentheses following the formulas of the substances. You use the following phase labels:
(g) - gas, (l) = liquid, (s) = solid, (aq) = aqueous (water) solution
When you use these labels, the previous equation becomes
2Na(s) + Cl2(g) ---------> 2NaCl(s)
What is the nuclide symbol for a nucleus that contains 38 protons and 50 neutrons?
Name the following compounds: a) N2O4, b) P4O6.
a) nitrogen tribromide
b) xenon tetroxide
The element with atomic number 38 (the number of protons in the nucleus) is strontium, symbol Sr. The mass number is 38 + 50 = 88. The symbol is 88/38 Sr.
a) dinitrogen tetroxide, b) tetraphosphorus hexoxide
a) NBr3
b) XeO4
