Transcript Rules for Naming Elements/Compounds

Rules for Naming
Elements/Compounds
The Rules
• Element names are abbreviated as follows:
– Element names are abbreviated using 1, 2 or 3
letters.
– The first letter is ALWAYS capitalized
– The second or third letter if present is NEVER
capitalized
– subscripts indicate the number of atoms present
of an element in a single molecule of an element
or compound
Practice
• For each Compound, list the symbol, the name
and the number of atoms of the elements
present:
• H2O
• NaOH
• H2SO4
• C6H12O6
• H2S2
Rules for Reading the Periodic Table
• Use the Table of Elements to find your element's atomic
number and atomic weight.
• atomic number is the number located in the upper left corner
• atomic weight is the number located on the bottom
• krypton:
Rules for Reading the Periodic Table
• The Number of Protons is...
– the atomic number . In the example, krypton's atomic number is 36.
This tells us that an atom of krypton has 36 protons in its nucleus.
• The Number of Electrons is...
– By definition, atoms have no overall electrical charge. That means that
there must be a balance between the positively charged protons and
the negatively charged electrons. Atoms must have equal numbers of
protons and electrons. In our example, an atom of krypton must
contain 36 electrons since it contains 36 protons.
Rules for Reading the Periodic Table
•
The Number of Neutrons is...
– The atomic weight is basically a measurement of the total number of particles
in an atom's nucleus.
– All you really need to find is something called the mass number.
– to find the mass number, all you need to do is round the atomic weight to the
nearest whole number.
– In the example, krypton's mass number is 84 since its atomic weight, 83.80,
rounds up to 84.
•
•
•
Mass Number = (Number of Protons) + (Number of Neutrons)
For krypton, this equation becomes:
84 = (Number of Protons) + (Number of Neutrons)
Let’s Summarize
• For any element:
• Number of Protons = Atomic Number
• Number of Electrons = Number of Protons =
Atomic Number
• Number of Neutrons = Mass Number - Atomic
Number
Let’s Practice
• Using the periodic table in your agenda, list the
number of protons, neutrons, and electrons for
the following elements:
•
•
•
•
•
Hydrogen
Potassium
Lithium
Nitrogen
Nickle
Quiz on Friday Will Include...
• Rules for writing chemical symbols.
• Be able to identify the number of atoms present
of each element in a given compound.
• What do subscripts mean?
• Know how to identify the number of atoms of an
element present in a compound using subscripts.
• Be able to find the number of protons, neutrons
and electrons of an element using the periodic
table.