CH1 Chemistry and measurements Flashcards
define chemistry
the study of the properties & behavior of matter
Matter is…
has mass and occupies space
property is …
any recognizable characteristic distinguishing it from other matter (100 elements)
Elements..
made up of unique atoms
Molecules are…
combinations of atoms in specific shapes
Macroscopic =
observable
Gas
no fixed volume/ shape (conforms to container/ compressible)
Liquid
Volume independent of container (no fixed shape/ incompressible)
Solid
Volume and shape independent of container (rigid/ incompressible)
Compounds…
combinations of elements (ex. H2O)
Law of Constant composition/ proportions
compound always consists of the same combination of elements
Mixtures
a combination of 2+ pure substances
Heterogenous mixtures
no uniform composition/ properties/ appearance
Homogenous mixtures
uniform throughout (aka SOLUTIONS)
Physical properties of matter
measured without changing the substance (no chemical change)
Chemical properties
how substances react or change to form different substances
Intensive properties
dont depend on the amount of substance present (temp./ melting pt./ density)
** give idea about the composition**
Extensive properties
depend on QUANTITY. (ex. mass/ volume)
Filtration
remove solid from liquid
Distillation
boil off components from mixture
The SCIENTIFIC METHOD
- Collect data
- Develop Hypothesis
- Test Hypo.
- Analyze & draw conclusion
Level of Confidence (LOC) - Hypothesis
Proposed explanation (50% confidence)
LOC- Theory
Broad generalization (90-95%)
LOC- Law
Universal Truth (100%)
Mass defined
Measure of the amount of an object (gravity dependent)
Temperature
flows from high to low temps`
Kelvin scale
freeze; 273.15 K
Boil ; 373.15 K
cm3 same as
- cc
- mL
dm3 same as
L
*L is n ot a SI unit
Density =
Mass/ volume (DMV)
Density unit =
g/cm3 OR g/ml
Precision
how well measure quantities agree with each other
Accuracy
measure quantities agree with true value
Addition and subtraction (sig. figs)
least number of decimal places
Multiplication/ division
report to least number of sig. figs