General Flashcards
Dimensional Analysis
a method for solving problems that involves canceling out the same units to multiply by a factor of 1.
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Celsius to Kelvin Conversion
K=C+273.15 C=K-273.15
Standard Atmospheric Pressure (1 atm)
1.013*10^5 Pa 101.3 kPa
Extensive Properties
depend on the amount of matter being measured
ex: mass, length, volume
Intensive Properties
does NOT depend on the amount of substance present
ex: density
Physical Change
any alteration to the size, shape, or state of a substance. same matter as before
Chemical Change
when matter changes into a new substance and has a new chemical property. alters the molecular makeup
Signs of a Chemical Change are…
.. change in color, change in odor, the formation of a solid or a gas, a change in energy
Precipitate
a new solid that is formed during a chemical reaction
Exothermic
a reaction that releases heat and energy
Endothermic
absorbs heat and energy
Viscosity
the speed at which molecules move in a liquid
Compressibility
measures the change in volume resulting from applied pressure
Sublimation is…..
a) common
b) rare
b) rare
it requires specific conditions to occur (ex: the right temperature and pressure)
A phase diagram is usually set up so that…
the pressure in atmospheres is plotted against the temperature in degrees Celsius or Kelvin
Why does a line on a phase diagram stay flat for some time before changing state again?
The substance must absorb enough heat so its molecules can move around enough to overcome the forces of attraction among them and then change states. All of the energy is put towards that change of state rather than the increase/decrease of temperature
Molecule
two or more atoms joining together chemically
Compound
a molecule the contains at least two DIFFERENT elements that are chemically combined in a FIXED RATIO. parts no longer retain their own properties.
Separate a mixture using….
filtration (insoluble solid from a liquid or solution)
chromatography (requires two different states of matter, used to test whether a liquid is a substance or mixture)
evaporation (soluble solid from a liquid)
extraction (isolates one compound from another)
distillation (purifies the liquid with heating and cooling)
Electronegativity increases from _____
- left to right
- bottom to top
Ionization energy increases from ____
- left to right
- bottom to top
Atomic Radius increases from ____
- right to left
- top to bottom
Electron Affinity increases from ____
-left to right
-top to bottom
(electron affinity is the neutral atom’s likelihood of gaining an electron)
(the only exception is fluorine; it is an anomaly and has a low electron affinity)
Heisenberg’s Uncertainty Principle
it is impossible to know both the speed and the position of an atom inside of its orbital
Metallic Bonding
the result of collectively shared electrons; metals share their electrons in a “sea”.
Except in rare and unstable cases, bonded carbon always has ___
4 bonds (NO LONE PAIRS WHEN BONDED
Reaction Pathway
The road that atoms and molecules take to turn from reactants to products.
Chemical compounds try to move towards a ___ energy state because it is more ____
lower; stable
Transition State
A higher energy state reactants go through to get to the products
How do you find the activation energy of a reaction?
Ea= (energy of transition state) - (change in energy)
The products of an exothermic reaction are more ___ than the reactants.
stable
What would an exothermic reaction look like?
A+B=C+D+energy
The products of an endothermic reaction are more ___ than the reactants.
unstable
What would an endothermic reaction look like?
A+B+energy=C+D
True or False: If a reaction requires energy to start, is it an endothermic reaction?
False. Just because a reaction requires energy to start does not mean it is an endothermic reaction.
Collision Theory
The frequency of the particles colliding with one another successfully and reacting determines the reaction rate
What 3 things must be true for a chemical reaction to happen?
1) Particles of the reactants must collide
2) The particles must have enough energy to react (Ea)
3) The particles must have the proper orientation
Chemical rates:
Increase or decrease; Concentration
Increase or decrease; Temperature
Increase or decrease; Catalysts
increase; increase; increase
What does a catalyst do?
A catalyst lowers the activation energy of a reaction by changing the reaction pathway to avoid the highest energy state. The amount of catalyst in a reaction does not change.
Acid strength increases as you _______
go down the periodic table and move from left to right in a row
What is radioactivity?
Radioactivity is the spontaneous breakdown of an unstable nucleus in an atom.
After a radioactive atom decays, the atom is ____.
lighter (fewer neutrons/protons)
How does a radioactive atom emit energy?
In the form of electromagnetic radiation and/or electromagnetic particles
Radioisotopes
the isotopes of an element that are unstable and therefore radioactive
What is the half-life of an atom/isotope?
The time it takes for one-half of the nuclei PRESENT to radioactively decay.
1 -> 0.5
2-> 2.5
What are the types of radiation?
Alpha radiation, beta radiation, gamma radiation
What happens when an atom goes through alpha decay?
The atom loses 2 neutrons and 2 protons. The atomic number decreases by 2 and the mass number decreases by 4.
What happens when an atom goes through beta decay?
One of the atom’s neutrons loses its neutral charge to become a proton so the atomic number increases by 1. Beta-radiation is stopped by solid materials.
What is nuclear fusion?
A nuclear reaction that occurs when the nuclei of two atoms join to make one of a larger atom. Gives off energy.
Nuclear fusion occurs only under very ___ conditions?
hot
What is nuclear fission?
A nuclear reaction that occurs when the nucleus of an atom splits into two smaller nuclei (usually about the same size). Vast amounts of energy are given off.
Combustion
an exothermic redox reaction between a substance and a gas that releases energy (fuel and oxidizer; releases energy)
