Download What is an isotope?

Oct 17 & Oct 20
QUIZ – LoC List #4
 Quiz starts 2 minutes after bell ring
 You have 4 minutes!
Warm-up#5: Summarize the
contributions to the Atomic Theory
Scientist
Experimental
Design
Democritus
--------------
Conclusion/
Contribution
Hypothesized
model
--------------
Niels Bohr
--------------
Quiz over history of atomic theory next time!
Draw what you think an atom looks like
• Draw a model of an atom on the front of a sticky note and
put your name on the back. Then stick it on the white
board.
• The Atom
Reviews of Atoms
• All matter is made up of elements
(e.g. carbon, hydrogen, etc.).
• The smallest part of an element is called an atom.
• Atom of different elements contain different numbers of
protons
• The mass of an atom is almost entirely due to the number of
protons and neutrons
Parts of Atoms - Subatomic Particles
Atom consists of two parts:
 The nucleus which contains:
• Protons
• Neutrons
 Orbiting Electrons
What are their charges?
Ions
The Atom (reminder)
The atom consists of two parts:
1. The nucleus which
contains:
protons
neutrons
2. Orbiting electrons
Ions have charges!
Charge: 0
-1
+1
Ions’ charges come from changes in ELECTRONS only!
Isotopes
What is an isotope?
 Number of protons for an atom of a specific
element never changes.
 Number of neutrons can change.
 Two atoms with equal protons but different
neutrons are called isotopes of each other.
 All atoms in existence are isotopes! Some
isotopes are just more common than others.
Isotopes
Atoms with equal protons but different number of neutrons
What do you notice that the isotopes have in common? What varies?
Isotope Notation
Mass number = number of protons + number of neutrons
X
Z
A
Element symbol
Atomic number = number of protons
Isotope Notation
Write isotope notation for each isotope of hydrogen below:
1
1
H
2
1
H
3
1
H
Hyphen Notation
• Write out the name of the element, then add a
hyphen (-), then the mass number.
• Write the hyphen notation for the
three isotopes of hydrogen.
Isotope Notation
Hyphen Notation
1
1
H
hydrogen-1
2
1
H
hydrogen-2
3
1
H
hydrogen-3
Summary
• If protons vary, the identity of the element changes
• oxygen has 8 protons; fluorine has 9 protons
• If neutrons vary, mass number changes and we have
different isotopes
• sulfur-32 has 16 neutrons; sulfur-33 has 17 neutrons
• If electrons vary, charge changes and we have different ions
• iron can lose two electrons to become Fe+2;
iron can also lose three electrons to form Fe+3
• All atoms are isotopes; isotopes can also become ions
Petri Dish Atoms Activity
• Draw a card – same number in same group
• You will work on 2 petri dishes at a time
• You must complete the chart for at least 6 petri dishes
• You will return the pair of petri dishes to the box
when you are finished and get 2 new ones.
• Isotope notation looks like this:
Mass number of this atom
Atomic number of this atom
40
19
K
+1
Ion charge, if it is not zero
Symbol of this element
• Quiz: Atomic Theory History—be ready!!
• Page 4: top half
• Sapling Practice Assignment due Monday night
• Sapling #1 due next Friday night
Homework