Science 7 Notes 13 Describe the structure of an .

Electron Be able to identify Atomic the number of , , and in an atom.

Identify the Structure of an atom: subatomic  Atoms are made of smaller called subatomic particles: particles and their charges?  Protons (positive)  Neutrons (neutral)

 Electrons (negative) Where are the subatomic particles located  Protons and neutrons are located in the nucleus (the center of the in an atom? atom).

 Electrons are orbiting the nucleus.

 The particles of opposite charges are attracted to each other, keeping electrons near the nucleus

 The # of electrons = # of protons

Structure of an Atom Subatomic Location Mass Nucleus of Positive 1 amu Proton the atom

Nucleus of Neutral 1 amu Neutron the atom

VERY Negative Basically no quickly mass orbiting the nucleus


Science 7 Notes 13

What does the atomic number of an atom represent?

How do the atomic numbers compare between different atoms?

If an atom has 12 protons, how Atomic Number: many electrons does it have?  Number of protons in an atom

 Each atom has a different number of protons

 In atoms the number of protons always equals the number of electrons (making the atom neutral)

Below are the nuclei of 3 atoms. Which atoms are shown? Where do you find the atomic 2 Protons = Atomic Number 2 mass of an element on the ?

How do you get the atomic number from this 4 Protons = Atomic Number 4 value?

How do you calculate the mass of an atom? 6 Protons = Atomic Number 6 What does the of an atom represent?  Mass Number for an atom = number of protons PLUS neutrons  For the Mass of a single atom, round the atomic mass on the periodic table to the nearest whole number


Science 7 Notes 13 Finding the Number of Neutrons  To Calculate:

How do you Atomic mass (protons + neutrons) determine the - Atomic number (protons only) number of neutrons an atom possesses? Number of neutrons in one atom

Find the following for the aluminum atom:

Atomic number Practice:

Atomic mass 1. Atomic number of carbon______Number of neutrons Number of 2. Atomic mass of carbon______protons

Number of 3. Mass number for a Carbon atom ______electrons 4. Number of neutrons in a carbon atom ______

5. Number of protons in a carbon atom______

6. Number of elections in a carbon atom ______

1. Atomic number of Molybdenum_____

2. Atomic mass of ______

3. Mass number for a Molybdenum atom ______

4. Number of neutrons in a Molybdenum atom ______

5. Number of protons in a Molybdenum atom______

6. Number of elections in a Molybdenum atom ______