CHEM 5013
Applied Chemical Principles
Chapter Two
Professor Bensley
Alfred State College
Chapter Objectives


Define the terms atom, molecule, isotope,
ion and functional group in your own
words.
Describe the nuclear model for the atom
and identify the numbers of protons,
electrons, and neutrons in a particular
isotope from its chemical symbol.
Chapter Objectives



Calculate the atomic mass of an element
from the masses and abundances of its
isotopes.
Determine the number of atoms in a
molecule from its chemical formula.
Describe the arrangement of elements in
the periodic table and explain the
usefulness of the table.
Chapter Objectives


Understand the basic differences between
organic and inorganic chemistry.
Use standard chemical nomenclature to
deduce the names of simple inorganic
compounds from their formulas or vice
versa.
Review

What is an element?

What is an atom?

What is a compound?
Atomic Structure of Matter

Matter is composed of:

Parts of the Atom:
1.
2.
“Nuclear Structure” of the Atom
Protons
Neutrons
Real Nuclear Structure
of the Atom

Electrons are
depicted as clouds
of negative charge
surrounding the
nucleus.
Nuclear Structure of the Atom

Atomic Number (Z):
Nuclear Structure of the Atom

Mass number (A):
+
Number of
Protons
+
=
number of
neutrons
=
Mass
Number
Atomic Number and Mass Number



Atomic Mass Units (amu)
1 amu =
Protons and neutrons nearly
more massive than electrons



Proton =
Neutron =
Electron =
times
Nuclear Structure of the Atom
Proton
Symbol
Location
Charge
Mass
Neutron
Electron
Isotopes

Isotopes:

Isotopic abundance:
Isotopes

Mass spectrometers can measure the
mass of atoms and isotopes.
Isotopes

Mass spectrum for carbon isotopes.
Atomic Symbols


We use atomic symbols to represent
atoms of the different elements.
Usually one or two letters


If two letters, Capital followed by lowercase
Examples:
Atomic Symbols

Atomic Symbol (Nuclide Symbol)
A
Z


E
Example:
 Chlorine exists as two isotopes: chlorine-35
and chlorine-37
 Written as:

What is the difference between chlorine-35
and chlorine-37?
Atomic Symbols
Atomic Masses
Atomic Masses

Fractional Abundance:

Relative atomic mass:



Carbon-12 =
Carbon-13 =
Weighted average mass =
Atomic Masses
Calculate the atomic mass of boron, B,
from the following data:
ISOTOPE
ISOTOPIC MASS (amu)
ABUNDANCE
B-10
B-11
10.013
11.009
FRACTIONAL
0.1978
0.8022
Periodic Table of the Elements


1869 – Dmitri Mendeleev
Found that when elements were arranged
in order of atomic weight, they could be
placed in horizontal rows, one row under
the other, so that the elements in vertical
columns have similar properties!
Periodic Table of the Elements
Periods



Referred to by numerical designations
Top row is period 1, etc.
The two rows that normally appear separately at
the bottom of the chart actually belong within the
body of the chart in periods 6 and 7.
Groups


Each group is identified by a numerical
designation. Over the years, two different
numbering systems have been developed.
Group (Family) Names
Periodic Table of the Elements

Do you see the heavy staircase in the
periodic table?
Ions



Ions:
What is the charge on an electron?
So what happens to the net charge if you
take one electron away? Add one on?
Ionic Substances

Two possibilities for formation of ions:
1.
Add an electron
2.
Lose an electron
Ions
Ions

Two fundamental ideas about electric
charge.
1.
2.
Ionic Bonding

Two depictions of a NaCl crystal.
Chemical Formulas



Chemical formula:
Convey relative proportions of atoms of
the different elements in the substance.
Examples:
Molecular Formulas
 Two
1.
types of Chemical Formulas:
Molecular Formulas
2.
Ionic Formulas
Ionic Formulas


Ionic formula:
What is the overall charge on an ionic
compound?
Ionic Formulas
What is the formula of magnesium nitride, which is
composed of the ions Mg2+ and N3-?
What is the formula of calcium phosphate which is
composed of the ions Ca 2+ and (PO4)3-?
What is the formula of magnesium oxide which is
composed of the ions Mg2+ and O2-?