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
what is a period
horizontal (numbered 1-7)
what is a group/family
vertical (numbered 1-18)
what are alkali metals
- extremely reactive
- soft, shiny and silver in colour
- compounds tend to be white and soluble in water
- group 1
what are alkaline earth metals
- shiny and silver but are not as soft as the alkali metals
- their compounds tend to be white, but they are less soluble than compounds formed by the alkali metals
- less reactive than alkali metals
- group 2
what are halogens
- family of non-metals
- consists of the elements fluorine, chlorine, bromine, and iodine
- these elements are poisonous and react readily with the alkali metals to form salts, such as sodium chloride (table salt)
- reactive
- group 17
what are noble gases
- very unreactive (stable)
- helium has a very low density, which is why helium filled balloons float, and its non-reactivity means it cannot catch fire (floating party balloons are filled with helium)
what are salts
- compounds produced in neutralization reactions between acids and bases
what is the atomic theory
an atom is the smallest part of an element that still has properties of that element
what are electrons, protons and neutrons (give symbol)
e- = electrons (negative) p = protons (positive) n = neutrons (no charge)
what is an atom
- most of an atom is empty space
- positive core nucleus
- atoms are not electrically charged
- protons + neutrons = 99.9% of the total mass of an atom
what is an energy level
can be thought of as a region of space near the nucleus that may be empty or may contain electrons
- an energy level can be empty, partly filled or completely filled
how many electrons can each energy level hold
the lowest energy level is the one closest to the nucleus - it can hold two electrons. the next energy level is larger and farther from the nucleus. it can hold up to 8 electrons (octet rule)
- electrons near the nucleus have the lowest energy
- electrons farther away have more energy
- electrons in the lowest energy levels are the most tightly held in the atom because they are the closest to the positively charged nucleus
what is the atomic number
- the number of protons it has
- elements on the periodic table are arranged according to increasing atomic number
mass number and atomic molar mass
- to help distinguish between the isotopes of an element each isotope is given a number called the mass number
- the mass number is an integer equal to the total number of protons and neutrons in the nucleus of an atom. electrons are not included in the mass number because their mass is so small
what is an isotope
atoms of the same element that contain different numbers of neutrons are called isotopes
how do you find the number of neutrons
number of neutrons = mass number - atomic number (protons)
how do you find the mass number
mass number = atomic number (protons) + neutrons
what is ionization
the atoms of most elements will either gain or lose one or more of their outermost electrons. the process of gaining or losing electrons is called ionization and it results in the formation of ions
what is an ion
an ion is an electrically charged atom or group of atoms
what does ionization result in
ionization results in metals and non-metals forming compounds
what are cation
cations are positively charged ions (cats are a positive thing)
- most cations form when metal atoms lost electrons. when a cation is forming, the lost electrons usually move to another atom. electrons are negatively charged. when they leave an atom, the ion that remains is positively charged because it now has more protons than electrons
what are anions
negatively charged ions are called anions - most anions form when non-metal atoms gain electrons
what is an ionic compound
ionic compound - metal + non-metal (cation + anion) (positive + negative)
what are valence electrons
the electrons in the outer energy level
- elements are stable (un reactive) when their valence (outermost) energy level is full
- elements in the same family have the same number of valence electrons
what is valence
the tendency to gain or lose electrons
what is valence number
the number of electrons an element can gain or lose to combine with other elements
what is the period number
number of occupied energy levels
what is the octet rule
states that atoms bond in such a way as to have eight electrons in their valence energy level. This is just another way to say that atoms tend to be stable with full outer energy levels (also called the rule of eight)
what is I.U.P.A.C
the international union of pure and applied chemistry - rules for naming compounds worldwide
define crystal lattice - acid, molecular, or ionic compound
ions grouped together in an organized ray (ionic)
what is ionic bonding
both are stable
what are ionic properties
- conducts electricity
- solid at room temperature
- high melting point
what does (aq) stand for
the subscript (aq) stands for aqueous. this means that the element or compound is dissolved in water
how do you name ionic compounds
- metal written first (cation)
2. non-metal written second, ending changed to ide (anion)
what is the formula for ionic compounds
- identify each element and its ion charge
- swap and drop the number from the ion charge
- put the symbols together and get rid of charge values
for an ionic compound the charge of the cation and the anion needs to be neutral
the positive and negative ions are attracted to one another, and the compound is neutral
what are multivalent elements
elements with more than one stable ion are called multivalent elements
- ionic compounds containing multivalent elements must have roman numerals in their names to indicate which ion is forming that compound
what are multivalent elements
elements with more than one stable ion are called multivalent elements
- ionic compounds containing multivalent elements must have roman numerals in their names to indicate which ion is forming that compound
what is a polyatomic ion
- several non-metallic atoms joined together
- “poly” means “many”
- ions that are made up of many atoms
what are the suffixes in polyatomic ions
two most common suffixes used in naming polyatomic ions are “-ate” and “-ite”
“-ate” means more oxygen atoms
formula for writing compounds containing polyatomic ions
- name the cation followed by the anion
- treat polyatomic as if it was one atom
- (same steps for formula)
- brackets show the ratio of ions
- the subscript outside the bracket applies to all the elements inside the brackets
what does (s) mean
a substance that does not dissolve well is considered slightly soluble - chemical formula would have (s) subscript
what is a precipitate
a solid that forms from a solution
what is a molecule
forms when two or more non-metal atoms bond together, forming covalent bonds
- can be atoms of different elements or atoms of the same element
what is a covalent bond
- electrons are shared by the atoms
formula for naming molecular compounds (NO hydrogen)
- use prefixes to tell how many atoms are in the molecule (mono, di, tri, tetra)
1. name the first element
2. name the second element, with suffix “-ide”
3. add prefixes to represent the number of each type of atom
To write the formula: use the prefix as subscripts
MEMORIZE compounds (WITH hydrogen)
green flash cards
what is an acid? what are acids properties
acid - pH less than 7 - sour taste - not slippery - reacts with metal Acids - H tends to appear on the left of acids
what is a base? what are its properties
base - pH more than 7
- tastes bitter
- slippery (ex. soap)
- does not react with metal
what is pH
pH is a measure of the number of hydrogen ions in a solution
what is a buffer
buffer: a substance that keeps the pH of solution nearly constant despite the addition of a small amount of acid or base
what is an indicator
change colour depending on the pH of solution
litmus paper
acid turns blue litmus paper > red
bases turn red litmus paper > blue
Naming Acids
hydrogen + other non-metal & the anion ends in “-ide”
- use prefix “hydro-“ and suffix “-ic”
naming acids containing oxygen
- if the anion ends in “-ate” (ex. sulfate), the acid name ends in “-ic”. (NO prefix)
- the the anion ends in “-ite” (ex. nitrite), the acid name ends in “-ous” (NO prefix)
ACIDS = ALL HAVE H FIRST
IONIC = METAL + NON-METAL
MOLECULAR = 2 NON-METALS (except for table)
naming bases
presence of hydroxide ion (OH) with a metal ion or ammonium ion usually indicated something is basic (ex. NaOH (sodium hydroxide) forms a base when dissolved in water)
note: same as naming ionic compounds
define neutralization
reaction between acid and base that forms water and salt
what is the mole
quantity that chemists use to measure elements and compounds
(dozen = 12)
what is molar mass
the mass of 1 mole of a substance
symbol: m
units: g/mol
how to calculate molar mass
- need chemical formula
- break up into elements
- look up each elements atomic molar mass
- add up each elements molar mass of substance
what is the mole equation
M = m/n
m = M x n
n = m/M
list 5 indications that a chemical reaction is taking place
- colour change
- temperature change
- formation of precipitate
- formation of gas
- corrosion of metal
