Download 9 19 -1 atomic number mass number charge

Atom review
Atoms are composed of three fundamental particles;
Protons
Located in the nucleus
Mass of ~1 amu
Charge of +1
Neutrons
Located in the nucleus
Mass of ~1 amu
Charge of 0
Electrons
Located outside of the nucleus (more on this later)
Mass of ~0 amu
Charge of -1
There are 118 different types of atoms, called elements: 94 of these occur
naturally, and another 14 have been observed under artificial conditions (as of
March 2010). Elements are defined by the number of protons in the nucleus.
For example, everything that has 9 protons is fluorine, and every fluorine has 9
protons. We often use a 1 or 2 letter abbreviation for an element, called the
atomic symbol. This is usually fairly self explanatory (C for carbon, H for
hydrogen), though in some cases the abbreviation comes from the Latin, Greek
or German name for that element. For instance, silver is Ag, which is derived
from the Latin argentum.
The elements are arranged on the periodic table in rows of increasing atomic
number. Elements within a column have similar properties
Even though all atoms of the same element have the same number of protons,
there can be differences in the numbers of neutrons and electrons. So, instead
of simply writing fluorine or F (the atomic symbol for fluorine), you might write
something like this:
19
-1
F
9
The subscripted and superscripted numbers are the atomic number, mass
number, and the charge.
mass number
19
atomic number
9
F
-1
charge
Atomic number - This is the number of protons in the nucleus. Fluorine has an
atomic number of 9, and therefore has 9 protons. All atoms of an element have
the same atomic number, by definition.
Mass number - This is the total number of nucleons, or protons and neutrons.
You can get the number of neutrons by simple subtraction. In this case, the
fluorine has 10 neutrons. Atoms of the same element can have different mass
numbers, and these are called isotopes. Isotopes do not differ in their bonding
properties, so within organic chemistry we will not be overly concerned with
differences in the number of neutrons.
Charge - This is the overall charge. Since neutrons are neutral, they do not
affect the charge at all. Therefore the overall charge is the balance between the
positively charged protons and the negatively charged electrons. A neutral atom
has the same number of protons and electrons. A charged atom, called an ion,
has an imbalance. If there are more protons than electrons, the ion will be
positive, if there are more electrons than protons the ion will be negative. In the
fluorine above, there are 10 electrons, since the charge is -1 and there are 9
positively charged protons.
You should be able to recognize the parts of the atom, know where they are, and
know how many there are in a given example.