21 Atom Reminders: September 23 Warm - Up: proton, neutron Today: 1. Check Density HW 2. Notes: Atoms 3. Study Guides Six Weeks Test Thursday Reminders:

36. proton positively charged subatomic particle found in nucleus of an atom Draw it: Connect it: found in nucleus heavy, 1 amu

37 . neutron neutral subatomic particle found in nucleus of an atom Draw it: Connect it: no charge heavy, 1 amu

Notice the location of each particle!!! HELIUM ATOM Shell proton N + - + - N neutron electron Notice the location of each particle!!!

Let’s Explore some Models of Atoms... Activity: Observe the “petri dish” model of an atom. Draw what you see and write at least three observations. Complete the chart & Questions.

Petri Dish Atom Model + + +

Notes: Parts of an Atom There are two main regions within an atom: -the NUCLEUS is located in the center of the atom and contains the protons and the neutrons (it is the denser part because it has the larger massive particles) -the ELECTRON cloud that surrounds the nucleus and contains electrons, makes up most of the volume of atom, it is 100, 000 times bigger than nucleus)

Atoms are made up of three main subatomic particles: PROTONS have a positive (+) charge and are located in the nucleus. NEUTRONS have no charge and are located in the nucleus. ELECTRONS have a negative (-) charge and are located outside the nucleus.

In any NEUTRAL atom, three things are equal---- atomic number, number of electrons, & number of protons To remember this, think of the word APE : Atomic # All three are equal. If Protons you know one, you Electrons know the other two.

Determining the Identity of an Element Each element on the Periodic Table is made of only one kind of atom. The number of protons determines an element’s IDENTITY. The number of protons is represented by the ATOMIC NUMBER. If you interpret the the information on the Periodic Table, you can find the number of subatomic particles in an atom of a given element.

C 6 Atomic number element symbol Carbon 12.011 element name atomic mass

To find the neutrons in the nucleus remember MAN : Mass number - Atomic # = Neutrons

To find the subatomic particles of any atom remember the mneumonic: APE MAN

Draw this chart on the back of your notes. ATOMIC STRUCTURE Draw this chart on the back of your notes. Particle Charge Mass proton + charge 1 neutron No charge 1 electron - charge

What makes a Hydrogen atom different from a Helium atom?

ATOMIC STRUCTURE Did you notice that… Electrons are arranged in Energy Levels or Shells around the nucleus of an atom. 32 18 8 8 2 P + n

Notice the location of each particle!!! HELIUM ATOM Shell proton N + - + - N neutron electron Notice the location of each particle!!!

He 2 4 ATOMIC STRUCTURE ALL atoms are NEUTRAL!!!! Therefore, Atomic number the number of protons in an atom Atomic mass 4 the number of protons and neutrons in an atom ALL atoms are NEUTRAL!!!! Therefore, # of electrons = # of protons

ATOMIC STRUCTURE RULES!!! The Atomic Number = # of protons in the nucleus. The Atomic Mass = # of Protons + Neutrons The number of Protons = Number of Electrons. Electrons orbit the nucleus in energy levels or electron shells. Each shell can only carry a set number of electrons. 2, 8, 8, 18, 32

Making a Model of the Atom Electrons NUCLEUS Protons Neutrons

HYDROGEN ___ e - 1 ___ P + ___ n 1 P = __ e = __ N = __

HELIUM ___ e - 2 ___ P + ___ n 2 2 P = __ e = __ N = __

LITHIUM ___ e - 3 ___ P + ___ n 3 4 P = __ e = __ N = __

BERYLLIUM ___ e - 4 ___ P + ___ n 4 5 P = __ e = __ N = __

BORON ___ e - 5 ___ P + ___ n 5 6 P = __ e = __ N = __

CARBON ___ e - 6 ___ P + ___ n 6 6 P = __ e = __ N = __

Now Use the White Board to draw the following atoms…

NITROGEN ___ e - 7 ___ P + ___ n 7 7 P = __ e = __ N = __

Complete the Chlorine atom on your own.

Fe2O3 chemical formula There are ___ elements in the formula. There are ___ atoms in the formula.