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In the NFPA safety diamond, what does the yellow color stand for?
Unstability/Reactivity Red? Flammability Blue? Health
What is the rule for multiplication/division using significant figures?
Round your answer to the least number of sig figs.
What is the rule for addition/subtraction using significant figures?
Round your answer to the least number of decimal places.
Round the following number to 2 significant figures:
3071.012 Answer: 3100 Round the same number to 2 decimal
places. 3071.01
What type of mixture is shown below?
Homogeneous Mixture Alloy
Define the term heterogeneous mixture and give 2 examples.
What happens to an atom when we have 2 more protons than electrons.
It IONIZES and becomes a cation with an oxidation number of +2
Define Ion:
What scientist used cathode ray tubes in his experiments?
JJ Thomson
What subatomic particle did he identify?
Electrons
Round the following number to 3 decimal places:
5412.02580 Answer: 5412.026 Round the same number to 3 sig.
figs. 5410
Who conducted the gold foil experiment? Ernest Rutherford
What did he conclude from his findings?
Ernest Rutherford concluded that atoms were mostly empty space with very a very dense positively charged nucleus.
Who proposed that electrons traveled in fixed paths around the nucleus?
Neils Bohr What was he trying to explain?
Round the following number to 3 Significant figures.
0.0095661 Answer: 0.00957 Round the same number to 2
decimal places
Why do scientist have to use significant figures?
Calculations cannot be more accurate than their measurements.
What subatomic particle has the same mass as a proton.
Neutron What’s the difference between them? Neutrons have no charge
Round the following number to 2 decimal places.
109.0053 Answer: 109.01 Round the same number to 1 sig.
fig.
What is meant by oxidation number?
The actual charge of an ion.
How do we know what is the oxidation number of an atom?
By looking at the periodic table, # of valence electrons.
a form of notation which shows how the electrons are distributed among the various atomic orbital and energy levels.
The format consists of a series of numbers, letters and superscripts as shown below:
1s2