Chemistry Flashcards
What does WHMIS mean?
Workplace Hazardous Materials Information System
- symbols are designed to help warn and protect people who use hazardous materials at work
What does SDS mean? What type of information is found on this sheet?
safety data sheet
- how to handle
- warnings/precautions
- information about products
What is a pure substance
all particles are identical (1 distinct melting and boiling point)
- elements
- compounds
what is an element
made of only one type of atom (e.g gold)
what is a compounds
two or more elements in specific ration (eg. water)
what is a mixture
combination of pure substances (different melting point/boiling point)
- solution
- mechanical mixture
- suspension
- colloid
what is a solution
the separate components are not visible (eg. sugar dissolved in water)…light will go through it
what is a mechanical mixture
the different substances are visible (eg. soil, chocolate chip cookie)
what is a suspension
the components are in different states. easily separated (eg. mud-suspension of dirt in water, ketchup)
what is a colloid
similar to suspension but the suspended substance cannot be easily separated from other substances… opaque (light will not go through it) eg. milk
list the physical properties
- boiling point or condensation point
- melting point or freezing point
- malleability (ability to be rolled into sheets)
- ductility (ability to stretch)
- colour
- state
- solubility
- crystal formation
- conductivity
- magnetism (attraction between objects)
physical properties: describe the physical appearance and composition of a substance
list the chemical properties
- ability to burn (flame, heat, light)
- flash point (temperature needed to ignite a flame)
- behaviour in air (tendency to degrade, react, or tarnish)
- reaction with water (tendency to corrode or dissolve)
- reaction with acids (corrosion)
- reaction to heat (tendency to melt or decompose)
- reaction to red and blue litmus (red - acid; blue - base; no colour change - neutral)
chemical properties: describe the reactivity of a substance
know the hazard each WHMIS symbol represents
know the hazard symbols (shape + colour)
yellow triangle - caution
orange diamond - warning
red octagon - danger
what are the properties of metal
- conductive of heat + electricity
- malleable
- ductile
- lustre
- solid at room temp
what is homogeneous
looks like one
what is heterogeneous
different
what is evidence of a chemical change
- precipitate forms
- unexplainable colour change
- energy is given off
- odour
- gas is given off
what is a chemical reaction? what changes occur in a chemical reaction
- all reactions involved in the production of new substances with their own characteristic properties (e.g state at room temperature, boiling point, colour and density)
- all chemical reactions involve the flow of energy. this may be detected by a change in temperature
- many reactions cause a phase change - formation of gas (bubbles) or solid (cloudiness)
define chemistry
understanding the nature of matter and changing matter in useful ways
what is food chemistry
cooking and preserving food (drying, heating, freezing, fermentation and chemical preservation)
define alloy
any mixture of metals
what is alchemy
- combination of magic + science
- contributed to development of chemistry
- discovered elements (e.g mercury)
- designed lab equipment
- developed scientific method
- chemistry developed very slowly during this time period because alchemists were secretive about their work because they wanted to make money
explain Aristotle’s description of matter
- believed that all matter was composed of combination of fire, earth, water and air
- he thought fire, earth, water and air were all continuous, which meant there was no such thing as a smallest piece
explain Democritus
- he proposed matter was made up of tiny particles that could not be divided into smaller pieces
- he called them ‘atomos,’ meaning invisible
- scientific investigation based on experimentation did not exist yet…so they didn’t test his ideas
who is John Dalton
john dalton imagined all atoms were like small spheres that varied in size, shape and colour
what is john daltons model of matter
- all matter is made of small invisible particles called atoms
- all atoms of an element are identical in properties such as size and mass
- atoms of different elements have different properties
- atoms of different elements combine in specific ration to form new substances
(atoms are tiny balls. the atoms of different elements were different in size and mass)
who is j.j thompson
he created the raisin bun/chocolate chip/plum pudding model
he discovered the electron
what is j.j thompson’s model
- all atoms are made of smaller subatomic particles
- atom is sphere of positive charge with negative particles imbedded
- negatively charged particles are electrons
what experiment did j.j thompson perform
vacuum tube: beam of particles produced in the vacuum have negative charge
- different elements produce similar beam
who is Hantaro Nagoaka
- created the planet model
- atom resembled Saturn with negative e- orbiting around the positive sphere
Who is ernest rutherford
- canadian
- worked with radioactive substances, discovered the nucleus
- predicted positively charged particles would pass through but some bounced back
what experiment did ernest rutherford perform
gold foil experiment
what was ernest rutherford’s model
- atom is mostly empty space, has a positively charged core = nucleus
- electrons move through the rest of atom’s volume
who is neils bohr
- electrons orbit nucleus at different energy levels
- higher energy levels are farther from the nucleus
- electrons can jump from one level to another if given energy
what experiment did niels bohr perform
examined light released by hydrogen atoms when they were made to glow in a tube
explain the quantum mechanical model of the atom
- based on the theory of quantum mechanics
- uses mathematical probability to describe how electrons exist in atoms
- each electron can be thought of as a cloud of negative charge (not in distinct orbits)
- electrons ‘occupy’ the whole space all at once at different energy levels
- the speed and location of the electrons cannot be determined at the same time
- nucleus contains protons - positive charge (neutrons - no charge)
what are metals
- most of the elements are metals
- most are silver or grey in colour and shiny
- conductors of electricity and heat
- most are solids at room temperature (25 degrees celsius) - except mercury
- they are malleable and ductile
- they react with other substances
- some highly reactive with air and water (not gold)
what are non-metals
- 17 elements
- grouped together for lack of resemblance to metals
- 11 of the metals are gases, 5 are solids, and 1 (bromine) is a red/brown liquid
- variation in colour (fluorine pale green, chlorine yellow)
- some non-metals exist in different forms (phosphorous has a red form and white form) - both forms stable at room temperature
- some non-metals are highly reactive (fluorine)
- about half of non-metals exist at 25 degrees as molecules (oxygen)
what are metalloids
- properties intermediate between metals and non-metals
- some metalloids conduct electricity, but not very well
- examples: silicon, metalloid, boron and arsenic
how does the periodic table organize elements
the periodic table organizes all the elements according to their chemical properties
how does the periodic table organize elements
the periodic table organizes all the elements according to their chemical properties