Semester 1 Final Flashcard

What is the difference between a chemical and physical change?
A chemical change is a change inwhich one or more substances are converted into a differnt.

Physical changes don’t alter the identity but the appearance of a substance

What is a substance?
A fixed composition that’s always homogenous
What does the arrow mean in a chemical equation?
means Yeilds to another reaction
How is a substance different from a mixture?
Every sample of a given pure substance has exactly the same characteristic properties. Every sample of a pure mixture has exactly the same composition.
The following are examples of what?

*chocolate melting when heated
*Cutting a piece of paper into pieces

PHysical Change
What is the purpose of a chemical equation?
To give a mathematical description of a chemical reaction
The Rules of Sig Figs?
Sig Fig if
*Not a zero
*To right of decimal and a non-zero number.
*Inbetween sig figs.
How many sig figs in 0.01035?
How many sig figs in 0.500?
How many sig figs in 9.0?
How many sig figs in 0.010?
How many sig figs in 5010?
What is the definition of accuracy?
How close an object is to a desired target
What is the definition of precision?
How many times an object hits near the same place
What Particles have a positive charge?
What particles have a negative charge?
What is the nucleus of an atom?
An atom’s positive center
What do neutrons do?
Help hold the neucleus together
What force holds electrons to an atom?
Opposite charges attract (electronic force)
What determines the atomic number of an element?
The number of protons
What determines the mass number of an element?
The number of protons and the number of neutrons.
What is the difference between mass number and the atomic mass on the periodic table?
The atomic mass the average occuring weight of the atom and the mass number is the sum of cell proton and neutron
What is Avagrado’s Number?
6.02 x 10^23
Evidence for electrons having limited allowed values of energy while in an atom is…
The emission light spectrum
List the sublevels from lowest to highest energy.
S, P, D, F
As an electron gains energy, is it most likely to be near the nucleus or less likely to be near the nucleus?
Less Likely

Name this



S Sub-level

What is this?



P Sub-level
What is the difference between a spin “up” and a spin “down” electron?
“up” contain one electron, “down” contain two
When a chemical reaction emits light but no heat, this is called?
What is the difference between Flourescence and Phosphorescence?
Floresence happens immediately, Phosphorescence takes a little while
How are flourescence and phosphorescence similar?
Both absorb light at high frequency.
What are the basic organizing prinicples of the modern periodic table?
It arranges the element by both the atomic number and it’s properties.
Where on the periodic table are the non-metals?
Why are the noble gases monstly unreactive?
Because extrastable mean loew energy configuration.
What does the stair-step on the periodic table represent?
The difference between the Metals and Non-metals
The transition metals are elements with their last electron in a __ Subshell
What is the Valence shell of an atom?
The subshell witht the highest coefficent
How is the radius of an atom defined?
It’s half the distance between the nuclei of identical atoms that are bound together.
Positive ions tend to be smaller than a neutral atom because…?
There’s fewer electrons repelling eachother so they are incapable of getting closer to eachother.
Where are the elements with the largest electronegativity?
The upper right of the P-Block.
Where are the largest Neutral Atoms?
Bottom of the S-Block
Ehhh… What the heck. Here’s a periodic table of elements. why not?



Nonmetals  = Group 14-18 on right side of stair step

Metals            = Group 13 (excluding stair step)

Transitive metals= D-Block and F-Block


When reading the Periodic table from left to right you see S, D, P, F versus it’s usual form of S, P, D, F (which list the blocks inorder from least to greatest)

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