UNIT B:CHEMISTRY AND MATTER SCIENCE 9

chemistry of science grade 9

WHMIS

Workplace hazardous informative system, are symbols that indicate some sort of hazard. If a symbol is in an octagon that means its contents is the hazard, if the symbol is in a triangle, the container is hazardous.

Matter

matter can be grouped into 3 different categories, solid, liquid, and gas, depending on the temperature

Freezing-liquid to solid

melting-solid to liquid

condensation-gas to liquid

boiling-liquid to gas

sublimation-solid to gas

deposition-gas to solid

Physical properties

Physical properties are the physical characteristics of a substance, when a substance goes through a physical change, or change of state, no new substance is made and can be easily reversed.

Examples of physical properties

melting point-the temperature in which a substance changes from solid to liquid

boiling point-temperature in which substance changes from liquid to gas

hardness-substance ability from getting scratched

malleability-substance can be pounded into sheets

ductility-substance can be stretched into long wire

crystal shape-shape of substance

solubility-ability of substance to be dissolved in another

density-how dense a substance is/mass in given volume

conductivity-substance ability to conduct heat and or electricity

Chemical properties

Chemical properties explain how a substance can interact with other substances, they cannot be easily reversed.

For example:Cooking an egg, when you cook an egg you cannot uncook it.

Chemical properties examples

\-reaction with acid

\-ability of getting burned

\-reaction in water

\-behaviour in air

\-reaction to heat

Pure substances

Pure substances is matter that cannot be broken down, they can be either elements or compounds

elements

element(s) are substances that cannot be broken down to any simpler substance, it is only one kind of matter.

Ex:Hg(mercury), O(oxygen), C(carbon), N(nitrogen)

compounds

when 2 or more elements combine chemically it creates a compound which is also considered a pure substance.

Ex:CO2(Carbon dioxide),H2O(hydrogen dioxide)

Mixtures

Mixtures is a combination of elements and pure substances, however they are not a pure substance because they aren’t chemically combined. The pure substances making up mixtures remain in original form even if they cannot be seen distinctively.

Mechanical mixtures aka heterogenous mixtures

Mechanical mixtures are mixtures that you can see the substances that make up the mixture.

ex:salad or soil

Solutions

Solutions are homogenous mixtures where a substance gets dissolved in another, and you cannot see the substances that make up the mixture

suspension

cloudy mixture that can be separated easily

colloid

cloudy mixture that cannot be separated easily

physical change

material changes from one state to another

chemical change

2 or more materials react and creates a new substance

Democritus

First used the word atomos(atoms), to describe the smallest particles that cannot be broke down anymore. Believed each type of matter was made up of different matters, and each material had its unique set of properties

Aristotle

Greek philisopher

Chemistry

Chemistry came from the word khemia was greek for juice or plant, juice from juniper tree was used to mummify bodies

Alchemy

early form of investigation of nature, combined science and spiritualism. Alchemists are not considered scientists, but was first to do chemical experiments having influence on modern chemistry and science.

Robert Boyle

He believed gases can be compressed, and believed that everything was made up of tiny particles, like democritus, that could group together in different combinations to form substances

Antoine Lavisier

Developed a naming system for chemicals, and defined hydrogen, oxygen, carbon, and other substances at that time. Is also known the father of chemistry

Combusion(1780)

Scientists found out air was necessary for combustion to occur

John Dalton theory aka billard ball model

First to define elements are pure substances, all atoms in an element had the same mass but no 2 elements had the same mass

JJ thomson theory aka rasin bun model

He used a cathode ray to find subatomic particles called electrons. He proposed the raisin bun model, which shows a positively charged sphere, with negative electrons embedded in it, making it balance out.

Hantaro Nagaoka theory

His theory was that negatively charged particles electrons orbited a positively charged nucleus. His theory was originally rejected because previous theories could not explain his

Rutherford model

From an experiment he did, he discovered a nucleus thats 1/10000th size of the atom, and it is positive. Also electrons surrounded the nucleus

Niels Bohr theory

Bohr discovered electron shells, electrons move in a specific orbit and can jump from each shell if the element loses or gains energy

Chadwick theory

Discovered that nucleus was made up of neutrons(neutral charged subatomic particle), and protons(positively charged subatomic particle). Protons and neutrons are similar in mass while electrons are lighter

Quantum Model

describes an atom of a cloud of electrons surrounding a nucleus.

Atom

Smallest part of an element that represents that element. Has a positively charged nucleus, that composes of neutrons(neutral) and protons(positive), and has a cloud of electrons(negative) surrounding it. The electrons are in electron shells, and can jump from each shell if the atom loses or gains energy. It is neutrally charged.

EXTRA INFO(you need to know)

\# of protons = # of electrons

centre of atoms aka nucleus are positively charged

Naming system of chemicals

John dalton developed a set of symbols to help communicate between chemists, then berzelius revised this by making it so that chemicals use the first or first 2 letters in its english or latin name, and making the 1st letter uppercase and 2nd letter lowercase

sorting out elements

Elements were listed based on atomic mass(mass number of one atom). John Newland created the law of octaves, which is a pattern in the periodic table which says that every 8 elements, or interval or 8 elements, had similar properties.

Mendeleev

He collected 63 elements at that time and sorted them based on their physical properties, boiling point, melting point, density, reactivity, etc. This allowed him to predict elements that didn’t exist yet.

Periodic table

Periods are the 7 horizontal rows, and families/groups are the 18 vertical rows

Atomic Number

\# of protons in element

\
\*\*# of protons=# of electrons

Mass number

\# of protons + # of electrons

Atomic Mass vs Mass number

Mass number is mass of one atom, atomic number is mass average of all atoms in element(decimal number because of isotopes)

Ion charge

An Ion is an atom of group of atoms that lost or gain electrons

metals vs non metals

Metals

\-shiny, malleable ductile

\-conductors

\-usually solid

\
Non metal

\-dull and brittle

\-insulators

Metalloids

Has both Metal and Non Metal properties

Akali metals

\-In group 1

\-Most reactive elements \*\*

Alkaline earth metals

\-Group 2

\-EXTREMELY REACTIVE, but not as reactive as alkaline metals,

\-2nd most reactive elements\*\*

Halogens

\-group 17

\-most reactive non metals\*\*

Noble gases

\-group 18

\-MOST STABLE ELEMENTS\*\*\*\*

Naming chemical formulas

Chemical formulas should always identify the elements that make up the compound, and how much of each elements. Metal always go first, and naming system is called nomenclature.

subscripts

subscripts is the little number beside a letter showing how much there is of that element

State + aqueous notation

When there is a little letters in brackets beside a compound, that basically says what state it is in. (s) stands for solid, (l) stands for liquid, (g) stands for gas, and (aq) says its in an aqueous solution

Polyatomic ions

A polyatomic ion is a group of atoms of certain elements combine to create a certain ion charge

Naming Ionic compounds

1\.Write the Metal element 1st

2\.write the non metal element 2nd and use the -ide suffix

or

2\.Write polyatomic ion BUT DO NOT USE -IDE SUFFIX

Elements with more than one ion charge

when elements use more than one ion charge we have to use roman numerals to distinguish which charge the element has

ex:Copper has 2 ion charges, 2+ and 1+, if it uses 2+ we write the element like Copper(II), but if it uses 1+ we use Copper(I)

Naming compounds

1\.Print out the elements name, metal first than non metal

2\.find out the charges of each element

3\.balance them out, so that both are equal

ex:

calcium chloride

Ca2+ Cl1-

CaCl2

Naming ionic compounds with polyatomic ions

if there is a polyatomic ion, and it balances out perfectly, then just write it out how its written. But if its unbalanced and the polyatomic ion has more than 1 atom write the polyatomic ion is brackets, then put the number of the polyatomic ion on the outside..

EX:Iron(III)carbonate

Fe 3+ CO3 2-

Fe2(CO3)3

Prefix rules for molecular compounds

Use rules to show how much atoms while naming molecular compounds:

1=mono

2=di

3=tri

4=tetra

5=penta

\
WHEN FIRST NON-METAL HAS ONLY ONE ATOM, DO NOT USE PREFIX MONO, BUT WHEN HAS MORE THAN ONE ATOM USE PREFIX(only applies to the first element)

Naming molecular compounds

1. Print out first element
2. Print out second element with -ide suffix
3. use prefixes BUT if first element only has one atom, then don’t use prefix for first element, doesn’t apply to 2nd element

Ex:CO2

Carbon oxide

Carbon Dioxide

\
Ex 2:N2O

Nitrogen Oxide

Dinitrogen Monoxide

Ionic Vs molecular compounds

Ionic

\-High boiling and melting point

\-conductors

\-distinct/nicer crystal shape

\-uses non metal and metal

\-uses roman numerals

\-uses ion charge

\
Molecular

\-Low boiling and melting point

\-insulators

\-rougher crystal shape

\-both non metal

\-uses prefixes

\-doesn’t use ion charge

Chemical reactions Reactants vs Products

Reactants are the materials at the start of the reaction, products are the materials and substances created from the reaction

Reactions(how to write them)

Plus symbols are used to separate reactants. A line is used to separate reactants from products, and plus symbol is used to separate products

EX:wood + oxygen → carbon dioxide + water + energy

Evidence of chemical change

\-odour

\-colour change

\-formation of solid or gas

\-release or absorption of energy

Exothermic reactions

Reactions where the energy is released. Energy would be placed with the products.

EX:If a beaker is hot, the beaker will be warm to touch because its __releasing energy__

Endothermic reactions

Reactions will energy is being absorbed. Energy would be placed with the reactants.

EX:If a beaker is cold, the beaker is cold to touch because its __absorbing energy__

Combustion

Chemical reaction that occurs when oxygen reacts with another substance to create a substance that gives off energy

* Reaction that causes something to burn or catch on fire
* known as a exothermic reaction

Corrosion

Slow chemical change when oxygen reacts with metal

* Rusting occurs
* exothermic reaction

Cellular respiration

A chemical reaction/change that happens in our bodies

* Glucose reacts with oxygen to create carbon dioxide, water, and energy.
* exothermic reaction
* Glucose + oxygen →Carbon dioxide + water(hydrogen dioxide) + energy

Law of conservation

Scientific law in which matter is not destroyed nor created during a chemical reaction. Proven in closed systems, and in open system, gas can escape still proven it exists

Closed systems

closed system means no extra material can enter nor leave, for matter to be conserved, the experiment must be done in a closed system.

Open systems

Open systems, the reaction is open to the environment. Even law of conservation cannot be proven in open systems, doesn’t mean it doesn’t happen. An opening allows gases to escape, meaning matter was still conserved.

Catalysts

Help a reaction go faster, doesn’t need to be apart of reaction, if there is no catalysts then there must be a higher temperature.

Concentration of reaction

The greater concentration of reactants, the faster the reaction. Because of higher concentrations, more atoms can react

Temperature of reaction

When heat is added to reactants, the faster the reaction. Since heating up a substance can make particles go faster, this can cause them to collide more often

Surface area of reaction

The high the surface area of reaction, there is more space exposed and available to react