SNC2D Grade 10 Academic Science – Chemistry Notes

Thanks, Jennifer!

Chemistry Study Notes

Element: pure substance that cannot be broken down
Period: row of elements on periodic table (SAME NUMBER OF ELECTRON SHELLS) Group: column of elements in periodic table with similar properties (SAME NUMBER OF VALENCE ELECTRONS)
Alkali metals: the elements in the first column, most reactive (group 1)
Alkaline earth metals: the elements in the second column, second most reactive (group 2) Halogens: elements in the seventeenth column, most reactive nonmetals (group 17)
Noble gases: elements in the eighteenth column, least reactive (group 18)
Properties of metal: metallic, conductive, malleable, solid
Properties of nonmetals: solid, gas, or liquid, brittle, dull, insulators
Protons: positive, in nucleus, atomic number
Electrons: negative, orbiting around nucleus, atomic number
Neutrons: neutral, in nucleus, rounded atomic mass minus atomic number Atoms: electrically neutral particle
Ions:
-charged particle that loses or gains electrons to have full outer orbit
-metals lose electrons to become positively charged CATIONS
-nonmetals gain electrons to become negatively charged ANIONS

Ionic compounds: composed of anions and cations, conduct electricity and dissolve in water, metal loses electron while nonmetal gains
Ionic bond: attraction of two oppositely charged ions, form between cation and anion, transfer or electrons

C o v a l e n t b o n d : s h a r i n g o f e l e c t r o n s b e t w e e n t w o n o n m e t a l s , f o r m s a m o l e c u l e
Molecular compounds: composed of molecules
Diatomic particles: elements that share a pair of electrons with the same element to reach stable octet (HOFBrINCl)

Naming:

Two Non-Metals (Molecular Binary Compounds):

-use prefix system:
1=mono 4=tetra 7=hepta 10:deca
2=di 5=penta 8=octa
3=tri 6=hexa 9=nona
-elements are written in order with the last element having an “ide” ending -ex: N2O4: DInitrogen TETRAoxide
-NO REDUCING
-IF FIRST ELEMENT ONLY HAS ONE, DO NOT USE “MONO”

One Metal and One Non-Metal (Ionic Binary Compounds):

-trend in charge numbers:
I II III IV V VI VII
+1 +2 +3 -/+4 -3 -2 -1
-for formula, write symbol for each element, metal first -write charge numbers as subscripts
-switch the charge numbers
-check if they can be REDUCED
-ex. Ba2+, S2-; Ba2S2; BaS
-ex. Al2O3: aluminum oxide

Transition Metals (Multiple Charge Number Ionic Compounds)

-metal has two or more charges (ex. Mercury)
-use STOCK SYSTEM to show charge number of metal then the nonmetal ending in “ide”
-do reverse-switcheroo to with the nonmetal and metal to determine which charge the metal has -ex. copper (II) fluoride is CuF2
-NO STOCK SYSTEM IF ELEMENT HAS ONLY 1 CHARGE (ex. Zn is only 2+)

Polyatomic Ionic Compounds:

Hydroxide: OH- Nitrate: NO3 – Chlorate: ClO3 – Carbonate: (CO3 ) 2 – Sulphate: (SO4 ) 2 – Phosphate: (PO4 ) 3 – Ammonium: NH4 +

-keep polyatomic compounds as one unit, do not break them apart
-use reverse switcheroo
-anion is named according to polyatomic ion rather than the names of the individual elements -ex. Mg2+,(NO3)-; Mg1(NO3)2;Mg(NO3)2

Law of Conservation of Mass
-in any given chemical reaction, the total mass of the reactants equals the total mass of the products, no new atoms are created and no atoms disappear
-reason why we balance chemical equations

Balancing Equations
-use coefficients in front of elements to balance the number of elements of both sides of the equation
-start by balancing the elements that occur only once on each side
-keep polyatomic ions together as 1 unit
-change “H2O” to “HOH” (one hydrogen, one hydroxide)
-have list of atom/element count

Types of Reactions

Synthesis

-two simple reactants combine to make a larger more complex product
-A +B=AB
-ex. zinc+sulphur=zinc sulfide (Zn+S= ZnS)
*sometimes in a reaction of aqueous reactants, one of the products is insoluble and appears in the solution as precipitate*

Decomposition

-large compounds are broken down into two smaller compounds of elements -A B=A+B
-ex. energy+water= hydrogen+oxygen (2H20= 2H2+O2)

Single Displacement

-one element replaces or displaces an element in a compound – A + B C = A C + B
-ex. copper+silver nitrate= copper(II) nitrate+silver

Double Displacement

–two elements in different compounds trade places

-A B+CD= AD+BC +-+-+–+

Complete Combustion

-oxygen is plentiful
-ONLY PRODUCTS: CO2 , H2 O
-hydrocarbon: any compound with H2, C, or O2 -ex. methane+oxygen= carbon dioxide+water -CH4+2O2=CO2+2H2O

Incomplete Combustion

-oxygen is limited
-ONLY PRODUCTS: C, CO, CO2, H2O
-ex. butane+oxygen=carbon dioxide+water+carbon monoxide+carbon (soot) -C4H10+5O2= 2CO2+5H2O+CO+C

-Combustion reactions are always synthesis (element+oxygen=oxide) – e x o t h e r m i c : r e l e a s e s h e a t
– e n d o t h e r m i c : a b s o r b s h e a t

Corrosion: breakdown of metal resulting from reactions with chemicals from the environment

ACIDS (H):

-neutralizes bases
-all acids have “hydro” in front
-are molecular
-tastes sour
-turns blue litmus paper red
-typically react with metals to produce hydrogen

-react with carbonate to produce CO2 gas
-conducts electricity (electrolytes)
-solution made of ions (electrolytes) can conduct electricity
-all acids have at least one hydrogen ion where they dissolve in water
-chemical formula always begins with ‘h’ and is (aq)
-BINARY ACIDS: CONTAIN 2 ELEMENTS (HF, HBr, HCl, H2S)
-OXYACIDS: HAS POLYATOMIC IONS (HC2H3O2, HNO3, H2CO3, H2SO4, H3PO4)
-THE NUMBER OF HYDROGENS IN THE ACID SHOWN IS EQUIVALENT TO THE VALUE OF THE CHARGE ON THE POLYATOMIC ION

BASES (OH):

-are ionic
-metal oxides react with water to form a base
-conduct electricity
-tastes bitter
-feels slippery
-changes red litmus paper blue
-are electrolytes but are made of ions
many bases contain hydroxide or carbonate ions
ex. NaOH, Ca(OH)2, NH4OH, Mg(OH)2, AL(OH)3, NaHCO3

Acid-Base Indicators
-natural or synthetic materials change colour to detect if it is basic or acidic

The pH Scale
-numerical scale from 0-14
-pH of 7 is neutral (ex, water)
-pH of 0-7 is more acidic
-pH of 7-14 is more basic
-acids form H+ ions in a solution
-bases have more OH than H+ which gives them their basic properties
-concentration of H+ ions determines how acidic or basic a solution is, where it is on the pH (power of hydrogen)

Neutralization
-occurs when acid and base are mixed
-product is a solution that is close to or is neutral (pH of 7) -PRODUCTS: WATER AND SALT (ANY IONIC COMPOUND) -SPECIFIC TYPE OF DOUBLE DISPLACEMENT REACTION

Indicator

Colour in Acid

Colour in Base

Bromothymol Blue

Yellow

Blue

Phenolphthalein

Colourless

Magenta/Pink

Litmus

Red

Blue

*NON-METAL OXIDES (NMOA) MIX WITH WATER TO PRODUCE ACID* *METAL OXIDE (MOB) MIX WITH WATER TO PRODUCE BASE*

Acid Precipitation
-emission of NOx ( NO2 a nd NO, vehicle engines) and SO2 (burning fossil fuels) combine with water to form acids in the environment
-freshwater is slightly acidic because of CO2
-harms fragile organisms and travels up food chain
-goes into soils and washes away essential metal ions
-weakens trees
-damage to steel structures, buildings, and monuments

Buffering
-buffering capacity: substance’s ability to resist changes in the pH level -limestone in soil has high buffering capacity

Scrubbers
-combustion gases fed through scrubber tower
-gasses showered through paste mixture of limestone and water
-limestone paste absorbs combustion gasses and convert it to CaSO3
-remaining gasses continue up scrubber tower and are released
-CaSO3 particles are removed when they fall down to bottom of the scrubber and can be converted to gypsum