Week 1 Flashcards
Define chemistry
The characterisation, composition and transformation of matter
Components of the scientific method
- Observations
- hypothesis
- experimentation
- theory, scientific law
Scientific theory
A well established hypothesis
Scientific law
Has no known exceptions, regarded as fact in modern science
International unit system
Metric system based on the SI units
What are the SI units
- kilogram (mass)
- metre (length)
- second (time)
- kelvin (temp)
- mole (amount of a substance)
- ampere (electric current)
- candela (luminous intensity)
Mass
measure f amount of matter in a body. Identical irrespective of location
Weight
Function of gravitational attraction and therefore varies
Litre
1 decimeter cubed
Angstrom
0.1nm (10 to the power of -10m), about the size of an atom
Density
mass/volume (SI unit is kg/m3)
kelvin
- temperature scale used in chemistry
- defined by absolute zero (temp at which molecular motion ceases)
Celcius to Kelvin
K = C* + 273
Basics of scientific notation
Numbers expressed as a number between 1 and 10 multiplied by 10 with a whole number power (exponential power)
Precision
how close your results are to the true results
Accuracy
how close the results are to each other
Rules for significant figures
- any non-zero digit is significant
- zeros that proceed the first non-zero digit are NOT significant
- zeros between non-zero digits are always significant
- zeros trailing non-zero digits are only significant if the number contains a decimal point
Leading zeros (significant numbers)
Any zeros before a non-zero digit
Adding/subtracting significant numbers
Significant figures to the right of the decimal point in the final answer are determined by the lowest number of significant figures to the right of the decimal point in the added numbers. Add together then round to that many significant numbers.
Multiplying/dividing significant figures
Significant figures in the product are determined by original number possessing the least number of significant figures
Matter
Any substance that occupies space and possesses mass
Primary states of matter
- solid: rigid, fixed shape/volume, incompressible
- liquid: fluid, fixed volume but no shape, incompressible
- gasses: fluid, no fixed volume/shape, compressible
Vapour
- gaseous matter at a liquid or solid boundary (in equilibrium with a solid or liquid)
Plasma
An electrically neutral gas of ions and electrons