thirsty for chemistry? i’ve gotta ask….. are you……
TRANSCRIPT
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