Thirsty for Chemistry? I’ve gotta ask….. Are You……

Thirsty for Chemistry?

I’ve gotta ask…..

Are You……

Color Change Demonstration

Get a beaker……

No, not that Beaker.

Color Change Demonstration

“Water”

Water + Baking Soda

“Fruit Punch” Phenolphthalein

(Think CSI)

“Milk” Barium Chloride

Dichromate + Hydrochloric acid

These are toxic, you cannot drink them!!

It’s All in the Atom

An Intro to Elements and the Periodic Table

Elements

• Robert Boyle (1627-1691) gave the basis for modern definition of an element

• “An element is a pure substance that cannot be chemically broken down into a simpler substance.

• Every element has it’s own atomic structure, which we call an atom

Parts of an Atom

• An atom is made up of 3 types of particles.

• 1) The electron (e-)– Has a charge of -1– Has relatively no mass– Is found in an orbital/shell, around the

nucleus of an atom

Parts of an Atom

• 2) The proton (p+)– Has a charge of +1– Has a mass of 1 amu– Amu = Atomic Mass Unit– Is found in the nucleus of the atom

Parts of an Atom

• 3) the neutron (n)– Has NO charge– Has a mass of 1 amu– Is found in the nucleus of the atom

Bohr Diagram of the Atom

• Niels Bohr was a Danish physicist.

• He proposed a model of an atom where:– protons and neutrons are located in the

centre of the atom (nucleus) – and the electrons move around the nucleus

in orbits called shells

Bohr Diagrams• Each shell can hold a specific number of

electrons.• K-shell is the first shell and can hold 2

electrons• L-shell is the second shell and can hold 8

electrons• M-shell is the third shell and can hold 8

electrons• Remember: Neutral atoms always have the

same number of electrons as protons (charges cancel)

Bohr Diagrams

• E.g-a boron atom has 5 p+, 5 e-, and 6 n. Draw the Bohr diagram:

++

++

+

Bohr Diagrams

• A beryillium atom has 4 p+, 4 e-, and 5n. Draw it:

++

+

+

Bohr Diagram

• A phosphorus atom has 15 p+, 15 e-, and 16 n. Draw it:

15 p+16 n

Reading from the Periodic Table

• Each element in the periodic table is represented by a symbol.

• Every symbol has an upper case letter.• Some symbols have two letters.

– The first is upper case – The second is lower case (e.g. Ca is

calcium)

• E.g.– C is the symbol for carbon

– Cl is the symbol for chlorine– Cu is the symbol for copper

Atomic Number

• Is the number of protons that an atom has.

• Each element has a unique atomic number.

• Every element is arranged according to atomic number on the periodic table.

• Atomic number = # of p+

Atomic Number

Is found in the top left-hand corner

Atomic Mass

• Is the mass of the atom in amu. • Since each proton has a mass of 1

amu, and each neutron has a mass of 1 amu, then the atomic mass is equal to the number of protons and neutrons.

• Atomic mass = # protons + # neutrons

Atomic Mass

• E.g. Nitrogen has 7 p+ and 7 n.

• So, atomic mass = 7 + 7 = 14 amu

Is found under the symbol.

On Your Periodic Table

Assignment

• Use your periodic table to fill in the table on page 4. We’ll do a few together.

Symbol Name Atomic

#

Atomic mass

P+ e- n

Li Lithium 3 7 3 3 4

O Oxygen 8 16 8 8 8

P Phosphorus 15 31 15 15 16

F Flourine 9 19 9 9 10

Br bromine 35 80 35 35 45

Fe iron 26 56 26 26 30

K potassium 19 39 19 19 20

Bi bismuth 83 210 83 83 127

Pb lead 82 207 82 82 125