Download structure of the atom

Name: ________________________________________________________ Date: _________ ABC# ________
STRUCTURE OF THE ATOM
I
Atoms consist of a nucleus surrounded by ______________________.
A. The NUCLEUS
1. The nucleus contains _______% of the mass of an atom.
2. The nucleus is made of _________________ and __________________ .
3. PROTONS have a _______________ charge.
(a) The mass of subatomic particles is measured with a unit called an _________ which stands for
__________________ ______________ ______________
(b) A proton has a mass of ________ amu."
4.
NEUTRONS have no charge, they are ________________________.
(a) The mass of a neutron is slightly greater than the mass of a proton but it is still said to have a
mass of __________ amu.
5. The ATOMIC NUMBER is the number of __________________ in the nucleus of an atom of.
(a) The ATOMIC NUMBER determines the identity of an element.
6. MASS NUMBER is the SUM of the _______________ and ________________ in the nucleus
of an atom.
(a) Atoms of the same element can have DIFFERENT NUMBERS OF NEUTRONS.
(b) Atoms of the same element with different numbers of neutrons are called ___________
(c) Example:
Oxygen: Atomic Number = ______ (This means that all oxygen atoms have have ____ protons)
99.8% of Oxygen atoms in nature have 8 protons and 8 neutrons for a mass number of _______
0.04% of Oxygen atoms in nature have 8 protons and 9 neutrons for a mass number of _______
0.02% of Oxygen atoms in nature have 8 protons and 10 neutrons for a mass number of ______
7. Any sample of an element as it occurs in nature is a mixture of different ISOTOPES (atoms with the
same number of protons but different numbers of neutrons). More Information
(a) The number BELOW THE SYMBOL for each element on the periodic table is called the
____________________ ___________________.
(b) The average mass number of all the natural isotopes of an element is called
the __________________ __________________
B. ELECTRONS
1. Electrons have a __________________ charge and have a mass of about 1/2000 of the mass of a
proton or neutron.
2. The mass of an electron is so small, it is almost __________________.
3. It is not possible to know exactly where the electrons are around the nucleus. We only know that
they exist somewhere within areas called _________________ around the nucleus..
4. The ORBITALS are arranged in _____________ ____________around the nucleus.
(a) Electrons with the ____________ ______________ are found near the nucleus.
(b) Electrons with the _____________ _____________ are found farther from the nucleus.
5. Energy Levels with the atom
(a) The first energy level can hold _______ electrons.
(b) The second energy level can hold ______ electron.
(c) The third energy level can hold ______ electrons.