Chemistry 9 Notes-Science 9 - Wikispacesmrsdaintreysonlineclassroom.wikispaces.com/file/view... · · 2017-01-23• Matter is anything that has mass and volume. It (matter) can

Chemistry Notes-‐ Science 9 Name:_________________________________

Daintrey’s Doings J_ 1

Chem-is-TRY Atomic Theory 1. Chemical VS Physical Change

• Chemical Change: Is a change in which new substances are formed. A chemical change produces a set of chemicals with is different from the set of chemicals, which existed before the change.

o Not reversible o New substances and properties form o May see an energy change

Examples: Cooking, Burning….

• Physical Change: Is a change in the phase (state: solid, liquid, gas) of a substance, such that no new substances are formed. A physical change does not change the set of chemicals involved.

o Able to reverse o No new substance, properties don’t change o Energy may occur

2. The Atom/Molecule/Matter

• An atom is the smallest particle of an element that retains the properties of the element. (i.e Elements are made up of atoms)

• A molecule is two or more atoms joined together. Molecules can have only one type of atom (element) OR can have more than one type of atom (compound). Example: O2 (element) and H2O (compound)

• Matter is anything that has mass and volume. It (matter) can be

classified into pure substances and mixtures.

o Pure Substance: contains only one type of particle § Element: Pure substance that cannot be changed into

anything smaller. § Atom: Smallest part of an element § Compound: pure substance that consists of two or more

elements.



o Mixtures: two or more pure substances mixed together.

§ Heterogeneous mixture: not uniform in composition. You

can see the different components in it. (i.e bits and bites)

§ Homogeneous mixture: uniform throughout. Cannot see the different components. (sugar water, pop, alloys, kool-aid)

• Subatomic particles are the particles that make up an atom. Look at the chart below:

3. Parts of the Atom- Subatomic Particles

Subatomic Particle Charge Mass Location Proton Positive (+ve) Has mass Nucleus Neutron Neutral Has mass Nucleus Electron Negative (-ve) Virtually no mass Orbits around the nucleus

• Protons and neutrons are held tightly together in

the center of the atom in a tiny region called the nucleus.

• Electrons exist in a region around the nucleus in regular patterns called shells or energy levels.



• The number of protons in a nucleus defines what that element is. You

can change the number of electrons and neutrons, but protons define what an element is.

4. How to Calculate Protons, Neutrons, and Electrons HEY STAR THIS! IT’S IMPORTANT! How to calculate Protons Neutrons and Electrons

o Number of protons (p) = atomic number

o Number of electrons (e) = number of protons (atomic #) in a NEUTRAL atom.

**In an ion (atom having a charge), can be more / less than the # of protons**

o # of neutron (n) = Atomic Mass – Atomic number (# of protons)

Atom Atomic Mass

Atomic Number

Protons Neutrons Electrons

Carbon Nitrogen Fluorine Chlorine Lithium



5. Atom vs Ion: Atoms have the same number of electrons and protons. Ions gain or lose electrons to become charged. They do this to form ionic bonds between metals and nonmetals. Use the charge listed on the periodic table to see how many electrons are gained or lost. Metals tend to loose electrons and form positive ions (cations) Nonmetals tend to gain electrons and form negative ions (anions)

Element Atomic Number

Number of Electrons in the Neutral atom

Ion Charge

Number of electrons in the

ion Fluorine 9 9 -1 10 Lithium 3 3 1+ 2 Sodium Magnesium Oxygen Rubidium 6. Organizing and knowing your Periodic Table Putting the Elements in Order A. Ordering by Properties

• Dmitri Mendeleev, created the periodic table in the mid 1800s. • He ordered the elements by properties and by increasing mass,

from left to right. B. Predicting with Properties:

• Based on groups and masses, chemists can predict properties of some of the elements, like boiling and melting point

• Pointing the way to the Future



• Mendeleev’s table wasn’t complete or perfect, but it helped point us in the correct direction for making the modern periodic table.

• Some metals and non-metals can only form an ion in one way. Calcium

forms a cation by losing 2 electrons to become Ca+2.

• Common ions formed by elements are shown in the upper right hand corner of the elements box in the periodic table.

• Notice how some metals have more than one possible ion. We call

these metals multivalent.

• Includes both metals and non-metals…separated by the staircase of fun. Metals on the left, non-metals on the top right.

• Elements are listed according to its atomic number. Each row is called

a period and each column is called a group or family.

• Elements in the same group / family have similar properties. What follows are the families / groups that you have to remember:

• Transition metals (multivalent): Block of elements that include groups

3 to group 12

• NON-METALS o UP a Group: In NON-METALS reactivity INCREASES as you

go UP Fluorine? A greedy, impatient beast when it comes to electron exchange manners.

o ACROSS a Period: In NON-METALS reactivity INCREASES as you go ACROSS

• METALS o DOWN a Group: In

METALS reactivity INCREASES as you go DOWN



o What doe metals do that make them metals? They are ductile, they conduct electricity, they are malleable, and they are solids are room temperature

o ACROSS a Period: In METALS reactivity DECREASES as you go ACROSS

Family Name

Elements Common Ion Charge

Group Number

Nobel Gases Special! DO

NOT react with anything.

He Ne Ar Kr Xe Rn None 18

Alkali Metals

Li Na K Rb Cs Fr +1 1 Highly reactive!

Alkaline Earth Metals

Be Mg Ca Sr Ba Ra +2 2

Halogens F Cl Br I At -1 17 Hydrogen H +1 or -1 1/17

Family Name Description Nobel Gases (He Ne Ar Kr Xe Rn) The atoms all have filled valence energy levels.

These elements have filled energy levels and do no easily bond with others

Alkali Metals (Li Na K Rb Cs Fr) These atoms each have one electron in their valence energy level. They lose the one electron easily to form +1 ions

Alkaline Earth Metals

(Be Mg Ca Sr Ba Ra) These atoms each have two electrons in their valence energy level. They lose two electrons to form +2 ions

Halogens (F Cl Br I At) The atoms each have seven electrons in their valence energy level. They gain one electron to form a -1 ion

Hydrogen (H) can lose an electron or gain one. This is what makes it so unique. H appears twice on the periodic table once as a metal and once as a non metal

* Hydrogen appears as both a metal and non-metal on the periodic table. It can use either covalent or ionic bonds* 7. Bohr Model Diagrams

• Niels Bohr discovered that electrons were arranged in energy levels or shells in specific patterns.



• Each shell can hold a certain number of electrons, no more, no less.

• A Bohr diagram (Bohr model) is a diagram (model) that shows how

many electrons are in each shell surrounding the nucleus.

• In Science 10, you only have to be able to draw and interpret the Bohr models for the first 20 elements. Use the following rules:

Rule for first 20 elements: 1st shell= 2 electrons 2nd shell = up to 8 electrons 3rd shell = up to 8 electrons 4th shell = 2 electrons ***not 100% true…but good enough for Sci 9***

• In drawing Bohr diagrams, start by finding out how many p, e and n’s there are. Electrons are the most important, as they are what really is shown.

For example: Bohr Model of Aluminum (Al) Protons Electrons Neutrons Bohr Model

How about a Sulphur ion with a –2 charge [S]-2? Protons Electrons Neutrons Bohr Model



Exam Question: What atom or ion does this Bohr diagram represent? • The outside shell of a Bohr diagram is called the valence shell

• Every element on the periodic table is trying to get a full valence

shell. For most elements that equals 8 electrons in the outer shell. This is called a “stable octet”

• Elements become ions trying to get to the 8 electrons in their outer

shell. They either gained extra electrons or give a few away. If you already have 8 electrons in your outer shell do you react well with other elements? * Think Noble Gases!

• There are patterns on the periodic table to tell you how many

electrons are in the outer “valence” shell of an atom. Column 1 = 1 valence electron Column 2 = 2 valence electrons Column 13 = 3 valence electrons Column 14 = 4 valence electrons Column 15 = 5 valence electrons Column 16 = 6 valence electrons Column 17 = 7 valence electrons Column 18 = 8 valence electrons

Example: Potassium Atom:

Ion:



8. Bonding Diagrams for Bohr Diagrams

• There are two types of chemical bonds, ionic and covalent. Atoms from compounds when the move close together and their valence electrons interact.

• In an ionic bond, electrons are transferred. The metal will transfer one or more electrons to the non-metal. Ionic compounds are made up of 1 metal and 1 non-metal. See the diagram below for Sodium Chloride (table salt).

Let’s draw one together:

MgCl2

• In a covalent bond, electrons are shared. A covalent compound is

formed when two non-metals share electrons.



• Electrons involved in bonding are sometimes called bonding electrons

(shocking) and electrons that are in valence shells, but not involved in the bond are called lone pairs.

Let’s draw one together: CH4

Sample Provincial Exam Question: Which two of the following atomic models represents elements that can easily combine with each other to form a covalent compound?

A. I and II B. I and IV C. II and III D. III and IV



9. A Lewis Diagram / Structures illustrates chemical bonding by showing only the valence electrons and the chemical symbol. Rules for Lewis Diagrams:

1. Dots represent electrons and are placed around the elements like dots on a compass.

2. Electron dots are placed singularly until the fifth electron is reached, then they are paired.

Bohr Lewis Dot Diagram (valence shell only)

Oxygen Oxygen

Fluorine Fluorine

Argon Argon

Exam Question: The Lewis diagram to the right represents two things. What are they?



Draw the following:

Hydrogen

Carbon Nitrogen

Hydrogen +1

Fluorine -1 Chlorine -1

10. Lewis Dot Diagrams for Ionic and Covalent Bonds

Rules for ionic compounds are as follows:

1. Draw the diagram for the positive ion (metal) using the common ion charge found on the periodic table.

2. Draw the diagram for the negative ion (non-metal) using the common ion charge found on the periodic table.



3. Remember that the metal will have lost electrons and the non-metal will have gained them.

4. Put brackets around each symbol with the charge written

outside the bracket on the top right.

Try these… MgO BaBr2

Rules for covalent compounds are as follows: 1. Draw out the element without using charges.

2. A line will represent the bond between the two elements

sharing electrons. Try these…

HF

CH4

NH3

C2H6

• A diatomic molecule is a pair of atoms that are joined by

covalent bonds. Some elements are more stable joined together than by themselves. There are 7 diatomic elements that you will have to remember. They are: H2, O2, F2, Br2, I2, Cl2 and N2

HOFBrINCl



• Can you see why we say hockey stick and puck? Look at the periodic

table.

• Always covalently bonded. (non-metals)

• Why do they always appear in pairs? Well if you look at their Lewis dot diagrams they all have the need for one valence electron to satisfy a shell. Let’s look at a few:

Flourine

Nitrogen

Hydrogen

Iodine

11. Writing Formulas for Ionic Compounds:

• The language of chemistry is based on abbreviations for the name of the elements. Such abbreviations are called chemical symbols.

• The first letter in the symbol is ALWAYS in upper case (capitals).

Second letters, if present, are ALWAYS in lower case.

THERE ARE TWO METHODS!!! Algebraic Sum (Never fails) In this method, the combining capacities (common charges) have to add to zero.



Here are the steps. We’ll look at Calcium + Fluorine or (Calcium Fluoride)

1. Write the symbols for the elements with their combining capacities.

Ca+2 F-1 *Note that a positive can only combine with a negative.*

2. The algebraic sum of the charges in a compound is zero. In other words, the charges should balance to zero.

As we can see, the Calcium is +2 and the Fluorine is -1. Thus, you will need 2 fluorine atoms for every 1 Calcium atom. Ca+2 F-1 F-1 +2 -2 = 0 As we can see, the Calcium is +2 and the Fluorine is -1. Thus, you will need 2 fluorine atoms for every 1 Calcium atom. The formula is CaF2 Criss-Cross Apple Sauce! As the name implies, this method involves a criss-cross. In this case, it is the combining capacities that are crossed. Here are the steps. Let’s look at Calcium + Fluorine again.



1. Write the symbols for the elements with their combining capacities.

Ca+2 F-1

2. Crossover the combining capacities as follows:

Ca+2 F-1

CaF2 (Note: + & - cancel out) **Caution: if you use this method, you will have to reduce the formula to lowest terms, just like fractions in math class.*** Example: Calcium and Oxygen Ca+2 O-2 (OR Calcium Oxide) Ca2O2 Ca2O2 must be reduced!!!!! The formula is CaO 12. Ionic Naming 1. Always write the metal ion first 2. Add the nonmetal second and add “ide” to it

Examples: Formula Name NaCl

BaBr2

AlF3

Mg3N2



13. Polyatomics

• Poly = Many • Atomics= Atoms

• In chemistry, there are groups of atoms that ‘act’ as a single atom.

These are called polyatomic ions

• Recall that metals have a positive charge (cation) and non-metals have a negative charge. Most polyatomics are non-metals, with ammonium (NH4

+) being the exception.

• The rules for writing formulas involving polyatomic ions are done in exactly the same way. The positive (metallic) ion is written first, followed by the negative ion. The algebraic sum must be equal to zero. (most polyatomic ions are negative ions)

How to use polyatomic ions for naming:

KCH3COO

(NH4)3P



How to use polyatomics for formula writing Name Ions Formula

Sodium Bisulphide

Calcium Phosphate

Calcium Carbonate

14. Multivalent Naming

• Multivalent means that there is more than one charge

• Use Roman numerals when naming compounds if the periodic table lists more than one charge.

• Recall that a multivalent element is one with more than one possible

charge (combining capacity).

• In order to write the formula, you MUST know which combining capacity to use. Luckily, it is in the name...Roman Numerals J

• Note that the combining capacity is given in roman numerals following

the element.



Roman Numerals: I =1 II =2 III =3 IV = 4 V =5 VI =6 The steps involved are exactly the same. If you use the criss-cross method, make sure you REDUCE J.

Example #1: Gold (III) oxide The roman numeral only have to do with the metal or the positive combining capacity. Method 1 Method 2 Au+3 O-2 or Au+3 O2- Au+3 O-2 O-2 Au2O3 +6 -6 = 0 Au2O3 Example #2: Nickel (II) phosphate Method 1 Method 2 Ni+2 PO4

-3 or Ni+2 PO4-3

Ni+2 PO4-3

Ni+2 Ni3(PO4)2 +6 -6 = 0 Ni3(PO4)2 ** Polyatomics ions are in brackets when there is more than one** Try these:



Compound Name Titanium (III) Oxide

Iron (III) Oxide Iron (IV) Sulphide

Ions & charges

Work shown

Formula

Now try going from the formula to the name: TIPS:

• Always look at the negative ion first! • Check to see if it’s a polyatomic • Balance charges to make sure that you have the correct positive ion

Examples: Fe (OH)2 _________________________________________________________

CrF _________________________________________________________

CuS ______________________________________

15. Covalent Compounds Naming and Formula Writing

Covalent compounds share electrons between two nonmetals.

Here are some rules that will help…

Rule 1: Write the name of the elements in the same order that they appear in the formula. The more metallic element is named first.



Rule 2: Drop the last syllable in the name of the final element and add –ide.

Rule 3: Add prefixes to the name of each element to indicate

the number of atoms of that element in each molecule of that compound. A prefix is ALWAYS added to the SECOND element, but only added to the first element if there is more than 1 atom.

Naming:

CO2

CO

CCl3

S2F10

H2O

You are given the following table in your data booklet to talk about the prefixes needed when naming covalent compound

carbon tetrabromide

sulphur trioxide

tetraphosphorus trisulfide

Diarsenic pentoxide

Diphosphorus pentoxide

Exam Questions What is the formula for the compound dinitrogen pentoxide?



16. Writing Chemical Equations: Now that we know how to name and write formulas this will help us write chemical equations. You simply have to convert from formula to words or from words to the formula Reactants + Reactants à Products Two things to be aware of when writing a chemical equation

a. Balancing coefficients: integers placed in front of formulas to balance the ratios in which the chemicals are consumed and produced.

b. States: letters indicating the state of the compound. (g) = gas, (l)= liquid (s)= solid

One water molecule H2O

Two water molecules 2H2O

Three water molecules 3H2O

One Hydrogen peroxide H2O2

Law of Conservation of Mass:



Mass cannot be created nor destroyed during a chemical reaction. The Amount of reactants must be equal to the mass of the products in a closed system. (What happens in an open system?)

1. Break it into sides…left and right 2. Right the atoms down the left side as they appear in the

equation. Keep polyatomics together!!!! 3. Do the same to the right side

(right down the atoms…SAME ORDER!) 4. Balance major atoms first (Metals / Non – Metals) 5. Balance water (H2O) and oxygen (O2) last.

Examples: ___ Al + ___ O2 → ___ Al2O3 ___ N2 + ___ H2 → ___ NH3

___ (NH4)3PO4 + ___ NaOH → ___ Na3PO4 + ___ NH3 + ___ H2O



Iron Solid plus Copper (II) Chloride yields Iron(II) Chloride plus copper Solid

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Chemistry 9 Notes-Science 9 - Wikispacesmrsdaintreysonlineclassroom.wikispaces.com/file/view... · · 2017-01-23• Matter is anything that has mass and volume. It (matter) can