Chemistry and Matter Flashcards
Extensive
Describes matter depending on the amount of matter in the sample.
Intensive
Describes matter depending on the type of matter, the contents (not the amount).
Physical Properties
A property which can be observed and measured without changing the material’s composition
Chemical Properties
- A property which can be observed by changing the composition of the material (after a chemical reaction)
- The ability to undergo a specific chemical change
Plasma
Formed at high temperatures; ionized phase of matter
Mixtures
A physical blend of two or more substances which have variable composition
Heterogenous Mixture
A mixture which is not uniform in composition (ex. chocolate-chip cookie)
Homogenous Mixtures
Same composition throughout; called “solutions” (powder-drinks, air)
Solutions
- Homogeneous Mixture
- Includes a ‘solute’ and ‘solvent’
- Mixed by molecule to molecule, and can occur between any state of matter
Phase
Any part of a sample with uniform composition of properties
ex. Homogeneous mixture consists of a phase, heterogeneous consists of 2+ phases
Separating Mixtures:
Differences in properties can be used to separate mixtures
Elements
Simplest kind of matter; cannot be broken down to have the same properties!
(One kind of matter)
Compounds
- Substances which can only be broken down by chemical methods
- Made of 2+ atoms that are chemically combined
- Will have completely different properties if broken down
Chemical Change
A change in which one or more substances is converted into new substances with change to composition.
Signs of a chemical change include heat and light.
Precipitate
A solid that separates from solution (won’t dissolve)
Signs of Chemical Change:
- Energy is absorbed or released (temp.)
- Color changes
- Gas production
- Precipitate
- Irreversibility
Law of Conservation of Mass
During any chemical reaction, the mass of the products is always equal to the mass of the reactants.
Symbols and Formulas:
Elements are represented by a 1 or 2 letter symbol; compounds are represented by a formula.
(ex. He = Helium; H20 = Water)
Atomic Number
The number of protons in an atom (in the nucleus)!
Elements are different because they have different amounts of protons.
Overall Charge:
All elements in nature have a neutral overall charge, therefore the number of protons equals the number of electrons.
Mass Number
The number of protons and neutrons in the nucleus of an isotope. (Rounded atomic mass)
Isotope
Element can vary based on the number of neutrons (and still be the same element).
Electron Mass:
9.11 x 10^-28
Much less mass than protons and Neutrons
Proton or Neutron Mass
1.67 x 10^-24
Majority of the Mass is in the Nucleus
Periodic Law
When elements are arranged in order of increasing atomic number, there is a periodic repetition of their physical and chemical properties.
3 classes of Elements
- Metals - Electrical conductors, have luster, ductile, malleable (can be shaped or drawn out)
- Non-Metals - Generally brittle and non-lustrous, poor conductors of heat and electricity (hard, but can snap or break)
- Metalloids - Properties are intermediate between metals and nonmetals.
Group of Elements
Group 1A - Alkali metals (very reactive; forms a base with water)
Group 2A - Alkaline Earth metals (do not dissolve well; reactive; Earth metals and also form base with water)
Group 7A - Halogens (wants one more electron)
Group 8A - Noble gases (stable and don’t react due to a full shell of electrons)
Solute
Something which dissolves in the solvent (usually liquid) to make a solution.
Solvent
Usually a liquid, does the dissolving of a solute to make a solution
3 Classes of Mixtures
- Solutions
- Colloid
- Suspension
Solution:
- Ex.
- Particle Type:
- Particle Size:
- Scatter Light?
- Settle while standing?
- Separate by filtration?
Always transparent, so that particles do not have to scatter light.
- Ex. - Salt water, air
- Particle Type - Ions, atoms
- Particle Size - Small
- Scatter Light? - No
- Settle while standing? - No
- Separate by filtration? - No
Colloid:
- Ex.
- Particle Type:
- Particle Size:
- Scatter Light?
- Settle while standing?
- Separate by filtration?
A mixture where one of the substances is split into small particles that are dispersed throughout another substance. The small particles are called colloidal particles.
- Ex. - Soot, fog
- Particle Type - Small clusters
- Particle Size - Medium
- Scatter Light? - Yes
- Settle while standing? - No
- Separate by filtration? - No
Suspension:
- Ex.
- Particle Type:
- Particle Size:
- Scatter Light?
- Settle while standing?
- Separate by filtration?
A heterogeneous mixture in which the solute particles do not dissolve in a liquid, and instead spread throughout the liquid.
- Ex. - Muddy water, Flour, Paint, Chalk in water, etc…
- Particle Type - Large clusters
- Particle Size - Large
- Scatter Light? - Yes
- Settle while standing? - Yes
- Separate by filtration? - Yes
Tyndall Effect
Light passes through a colloid or suspension (particles scatter light).
Emulsion
A mixture where two or more liquids are unblendable (such as oil and water), causing a liquid-liquid separation.
Periodic Table:
Displays the symbols and names of the elements, along with information about the structure of their atoms. (Atomic Number and mass)
Balanced Chemical Equation
- Atoms cannot be created or destroyed
- Same number of elements on both sides of the equation
Ex. 2_Na + 2_H2O –> _H2 + 2_NaOH
The Skeleton Equation
A chemical equation which does not indicate how many elements; meaning NOT balanced.
Ex. _Na + _H2O –> _H2 + _NaOH (Notice the Coefficients are missing)
” (aq) “ - after the chemical formula
Dissolved in water, an aqueous solution: NaCl (aq) is a salt water solution
arrow points up - after the chemical formula
Used after a product showing that a gas has been produced.
arrow points down - after the chemical formula
Used after a product indicating a solid has been produced
Rules of Balance (Chemical Equations):
- Assemble the correct formulas for all the reactants and products, using “+” and “–>”
- Count the number of atoms of each type appearing on both sides
- Balance the elements on at a time by adding coefficients (the numbers in front) where you need more – save balancing H and O until LAST! (Oxygen is last)
- Coefficient must be in the front!
- Subscript cannot be changed, only coefficients, or it becomes a different compound.
