Chem Midterm Concepts Flashcards
Accuracy
How close something is to its true value
Precision
How well experimental values agree with one another
How to find accuracy?
Calculate percent error
How to find precision?
Repeat the experiment
Base unit for mass
kilogram
Base unit for length
meter
Base unit for time
second
Base unit for temperature
kelvin
Theoretical yield
Maximum number that could have happened
Actual yield
Number that actually occured
Density
the degree of compactness of a substance
Density formula
d=m/v
Percent Error Formula
Abs(Theoretical-Experimental)/Theoretical
ANS*100
Percent Yield Formula
Actual Yield/Theoretical Yield
ANS*100
Law of Conservation of Matter
Matter can not be created nor destroyed in an isolated system
Chemical change
substance changes chemical composition
Physical change
substance changes physical properties, but its composition does not change
Examples of chemical change
Iron combining with water to make rust
Toast
Salt dissolving in water
Examples of physical change
ripping paper
water to ice
sugar mixing in water
Pure substance
fixed composition and properties
composed of 1 kind of molecule
Mixture
made up of 2 or more pure substances
Is a mixture chemical or physical?
Physical
Element
A pure substance
composed of all the same types of atoms
cannot be broken down any smaller
Compound
A pure substance
composed of all the same molecule
proportionally distributed
can be broken down into elements
Homogenous mixture
Particles of similar composition that are small and evenly distributed
Heterogenous mixture
Particles of different composition and particles are not evenly distributed
Example of a solution
Sugar water
Example of an alloy
Brass
Examples of colloid
Smoke
Dairy products
Examples of suspension
Oil and water
Muddy water
Who discovered the electron?
JJ Thomson
How was the electron discovered?
Through the cathode ray tube experiment
Who discovered the neutron?
James Chadwick
Who discovered the proton?
Ernest Rutherford
How was the proton discovered?
Gold foil experiment
showed there had to be positive space in atom because of the way rays bounced
Who first said matter is composed of atoms?
Democritus
Which subatomic particle has a positive charge?
Proton
Which subatomic particle is located in the nucleus?
Neutron and proton
Which subatomic particles are respsonible for the mass of an atom
Proton and neutron
Which subatomic particle identifies elements
Protons
Which subatomic particle identifies elements?
Protons
Which subatomic particle is responsible for the atomic number of the atom?
Protons
Which subatomic particle varies in isotopes?
Neutrons
Which subatomic particle has the smallest relative mass?
Electrons
Which subatomic particle varies in ions?
Electrons
Dalton’s model
Indivisible solid sphere
Thomson’s model
Plum pudding model
Rutherford’s model
shows a positive nucleus surrounded by electrons
Wavelength
the distance between any two points on a wave
Frequency
the numbers of cycles that pass through a point in an unit of time
Which color has the highest frequency?
Violet
Which color has the lowest frequency?
Red
Which type of radiation has the highest frequency?
Gamma rays
Which type of radiation has the lowest frequency?
Radio waves
What is the speed of light?
3.0 * 10^8
Wavelength formula
wavelength=speed/frequency
Specific heat
the amount of heat required to raise the temperature of one gram of a substance by one degree celcius
Specific heat formula
Q=mc(delta)t
Three different types of radioactive decay
Alpha
Beta
Gamma radiation
What element is an alpha particle similar to?
Helium
Alpha radiation calculations
looses 4 mass number
looses 2 atomic number
Beta particle
a fast moving electron emitted from the nucleus of an atom
When does beta decay occur?
When a neutron changes into a proton and an electron
Beta calculuations
Mass number stays the same
Atomic number raised by one
Gamma rays
high frequency
if an atom still has a lot of energy after beta/alpha decay a gamma ray will be emitted
Half-Life
The constant ratio of a substance undergoing exponential decay
