1.1 Matter and Measurement Flashcards
Anything that has mass and ocupies space
Matter
Matter is made up of atoms
Atoms = elements
* ~118
Matter comes in 3 major states: what are they
Solid
Liquid
Gas
Solids:
* Definite shape
* Definite volume
Liquid:
* No definite shape - think about pouring it into a container - does not keep its shape
* Definite volume
Gas:
* No definite shape
* No Definite volume (they will grealty expand if you put them in a container - depending on the size - so the volume is variable)
Most solids are crystalin solids - the atoms are arranged in a nice repeating structure
Those can be individual molecules or atoms
These atoms arent moving to any significant extent
In a liquid these molecules/atoms are able to move around a lot
In a gas these molecules are spread out and they’re moving
* typically moving faster than the molecules in a lquid
A substance that is only made up of 1 type of atom is called a
Element
Think pure Na+ metal - every atom is sodium = still an element
A substance that is made up of multiple elements
Compound
Think NaCl - this is a compound because there are multiple atoms in it
* its stil 1 substance, but made up of 2 types of atoms
You can say something like “I have the element Na in a compound” thats fine, you just can’t say I ahve the element NaCl because its not an element, its a compound
Some elements come in pairs in their elemental form (N2 is naturally occuring not just N)
* What are these called?
* Theres 7, what are they?
Diatomics (meaning we have 2 of them)
* N2, O2, F2, Cl2, Br2, I2, H2
Theres 7 of them and 6/7 of them actually form the number 7 on the periodic table (easy way to remember them)
You can also use the mneumonic “Never Have Fear of Ice Cold Bear”
Pure substance
* Can be just 1 element (O2)
* Can be just 1 compound (H2O) <– as long as I just have water and nothing else its a pure substance
* Either way we refer to it being a pure substance
Mixture
* Air (N2 + O2) <— air has different components that are together but not bonded (in water they’re actually bonded together = pure substance)
* Salt water (NaCl + H2O <– not bonded = mixture)
What are the two kinds of mixtures?
* Explain what each is
Homogeneous Mixture
* If you took samples all over it would have exactly the same amount of every component
* Its uniform throughout the mixture = homo
* Think air –> If i took it at anywhere in this room it would be the same (it would’ve equilibrated)
* Salt water - say i dissolved salt in water = dissolves uniformly in which case this would be the correct place for it
Heterogenous mixture
* If you took samples all over they would be different
* Salad <— depending on where you took that bite it would be different = non uniform
* Salt water - salt is only so soluble in water - meaning some will dissolve but the rest won’t and will sink to the bottom - meaning its not dissolved evenly in the volume of your container = heterogenous
Matter has both chemical and physical properties (you can have chemical changes and physical changes)
* If the change converts 1 substance into another substance is it a chemical change or a physical change?
* If the change does not convert one substance into a different substance what kind of change is it
1 substance to another = chemical change
* Lighting a peice of paper on fire
* Converting cellulose into CO2 and H2O = chemical change because you’re changing one substance into another substance
* Nail Rusting Fe2 + O2 –> Fe2O3 - this is a chemical change (oxidation) <– dont need to know this word yet
1 substance does not change to another = physical change
* Think ripping a peice of paper in half –> still made of paper –> physical change
* Dissolving salt in water (not actually breaking bonds, you still have salt in the water, think about evaporating the water, you still have salt in there)
* NaCl(s) –> NaCl(aq)
* the aq = aquious, and means some compound was dissolved in water
* Notice Salt is the same whether its solid or dissolved, meaning its a physical change because no bonds were impacted and we have the same compound
What are the 3 phases of matter
* when going between these 3 are we having chemical or physical changes?
Liquid
Solid
Gas
These are physical changes because we arent actually converting one susbtance into another. Liquid –> gas = the same molecules, no bonds are broken
Melting Ice
H2O(S) –> H2O(l)
* notice i wrote the state its in behind it
* notice again this is just a physical change
* water has a melting point of 32 degrees
Whats an intensive property?
* Whats an extensive property
The big difference is if size matters
Intensive property - size does not matter
* Melting point - melting point is the exact same temp regardless of how much water you have
* Density = Mass/Volume - this is tricky because both of these are extensive properties - its because they’re a ratio and even out
* Temperature - if i’ve got a glass of water and a swimming pool and they’re both sitting outside - well the size of the sample doesnt impact the temp - so size doesnt matter
Extensive properpty - size does matter
* Mass - think putting 2 different masses on a scale - the size of the sample tottaly affects that mass
* Volume <– impacted by size (will change based on the size of the sample)
Is density and intensive or extensive property?
Intensive - meaning that size doesnt affect it
Density = Mass/Volume - this is tricky because both of these are extensive properties - its because they’re a ratio and even out
Is Temperature an Intensive or Extensive property
Intensive
Temperature - if i’ve got a glass of water and a swimming pool and they’re both sitting outside - well the size of the sample doesnt impact the temp - so size doesnt matter
All of the above
Pure Substance = single element, or single atom
If it was a mixture of like NaCl and H2O then it would be incorrect
NaCl = pure compound (not a mixture)
O2 = pure element
H2O = pure compound
Ammonia
This is because ammonia is the only pure compound
Air, Coca Cola, Orange juice, salt water = mixture of multiple different things
Air
A homogeous mixture is a combination of two or more substances in which the composition is unifrom throughout. Air is a mixture of several gases and the composition is unfirom throughout
Liquid water is a single substance (single compound) rather than a mixture
A can of pain is heterogeneous mixure rather than homogenous and its composition is not uniform throughout (the components separate as it settles which si why it must be mixed before using)
Liquid nitrogen a single substance (single element) rather than a mixture
Metal rusting
because the actual chemical composition is changing
hail formation is that liquid water turning into a solid (not actaully changing chemcial composition)
Sublimation of ice (this is a phase change, meaning it doesnt change physically)
Meaning size does matter
* melting point –> the amont of snow doesnt change what its melting point is (if you have a glass of water or a swimming pool the meltoing point of the ice in it doesnt change) melting point of water is 0 either way
* Density = M/V - while both are extensive the ratio of the two cancel out, meaning density is intensive - wether you have a glass of water or a swimming pool of water the density of water doesnt change
* Volume - Correct (the amount of mass changes its volume)
* Temperature - doesnt change regardless of how big or small the sample is
* Bioling point - similar to meltoing point
Meaning size doesnt matter
Color and desnity are both indepndent of sample size and are intensive properties
F2 is a pure element - its diatomic as there are two fluorine atoms per molecule, but it is still just a single element
