Chemistry Quiz Two Notes

8/4/2019 Chemistry Quiz Two Notes

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Chemistry NotesPeriodic Table and Basic Bonding

Syed Kamran



10/4/2011

Syed Kamran - CourseCentral 1

Chemistry Notes

Periodic Table and Basic Bonding

PERIODIC T ABLE Presently there are 118 elements on the periodic table of elements, however more are

still being discovered. It is one the most useful tools to chemists. The table is organized so

that you can determine its physical properties just by looking at its position.

ElementsScientists have identified 92 naturally occurring elements and created about

26 others. The elements alone or in combinations, make up our bodies, our world, our

sun, and in fact, the entire universe.

Valence Electrons Valence electrons are the number of electrons at the outer energy level of an

atom. These are the electrons that are used when atoms bond together.

Main Categories of the Periodic Table

Metals: Metals are good conductors of

heat and electricity. They are shiny,

ductile, and malleable. Metal corrode

in water.

Non-Metals: Non-metals are poorconductors of heat and electricity. They

are not ductile, and malleable. Solid

non-metals are brittle, break easily

and are dull. Many non-metals are

gases.

Metalloids: Metalloids have properties of both metals and non-metals. They can be

shiny or dull. They can conduct heat and electricity, however not as well as metals.

They are also ductile, and malleable.

Groups and PeriodsWithin the Periodic table of elements, elements are also organized via groups

and periods.

Groups (families): Groups are the vertical columns that have similar properties.

Some of the columns have been given special names to distinguish them. All

elements in a family have the same number of valence electrons.



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Periods: Periods are the horizontal rows that do not have similar properties. Sizes of

atoms decrease as we move left to right across a period; this is due to the increasing

number of protons in the nucleus, resulting in a stronger electrical attraction

between the nucleus and electrons. In addition the electronegativity increase as you

move left to right across a period. The first element in a period is always an active

solid, and the last is always an inactive gas.

ClassesThere are many classes within the Periodic table of elements; most of the

elements have similar properties.

Hydrogen: The hydrogen square sits atop of Group 1, but it is not a member of that

family. It is a gas at room temperature. It has one proton and one electron in its

electron level.

Alkali Metals: The alkali family is found in the first column of the periodic table.

Atoms of the alkali metals have a single valence electron. They are shiny, have the

consistency of clay, and are easily cut with a knife. They are the most reactive

metals, and react violently with water. Alkali metals are never found as free

elements in nature, however always bonded with another element.

Alkaline Earth Metals: Have two valence electrons and are never found

uncombined in nature.

Transition Metals: They are good conductors of heat and electricity. Can

chemically combine with oxygen to form compounds.

Halogen Family: Halogens have seven valence electrons, why they are the most

active. They are never found free in nature.

Noble Gases: Noble gases are colorless and extremely unreactive. They outer most

energy level is full, and due to this they are called inert. They are found in small

amounts in earth’s atmosphere.

Rare Earth Elements: The thirty rare earth elements are composed of the

lanthanide and actinide series. Most of these elements are synthetic or man-made.

Groups (families) Periods



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DRAWING DIAGRAMS There are a couple of diagrams you need to be able to draw for the test. They are as

follows.

Bohr-Rutherford DiagramLets take an element, with an atomic number less than 20.

Oxygen

• Eight Protons

• Seven Neutrons

• Eight Electrons

Bohr-Rutherford Ion DiagramLets take an element, with an atomic number less than 20.

Oxide (II) ion

• Eight Protons

• Seven Neutrons

• Ten Electrons

Lewis DiagramsLets take any element for example Sodium it has the chemical symbol of Na.

Sodium

• The symbol represents neutrons, protons and all electrons excluding valance

electrons.

• Valences electrons are represented by dots on each side of the symbol.

• The order of placing the dots is Top, Bottom, Right, Left.

• Since Sodium has one valence electron it would look like this:

• With Ions will have the valence electron layer full with either

8 electrons or two.

8 P

8 N



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IONS

Introduction Atoms are made up of particles, which either have a positive charge or

negative charge. The positive or negative charges cancel each other out, so the net

charge in an atom is zero. The positively charged particle is called a proton, and thenegatively charged particle is called the electron. In atoms the protons are in the

center and the electrons are on the outside, only electrons can be removed from

atoms. If you add electrons to an atoms in becomes negatively charged, and if you

remove them they become positively charged. An atom with a positive or negative

charge is called an Ion.

Cations

Cations are ions with a positive charge. If an atom loses an electron

or more it is called cation.

Anions

Anions are ions with a negative charge. If an atom gains an electron

or more it is called an anion.

Why does this occur?

All atoms want to become stable, and in order to become

stable there outer most energy level must be

complete. To do this they can either lose an

electron and become a cation or gain an electron

and become anion. The atom will do what ever is

easier, in other words it would prefer losing an

electron instead on gaining seven in the following

case.

* Note: We only work with groups 1, 2,13,15,16,

and 17 when dealing with ions.

Naming IonsPositive Ions: The name is the same of the element followed by ion.

E.g. Na+ = Sodium ion

Negative Ions: The name is determined by removing the end and adding ide.

E.g. O- = Oxide ion



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IONIC BONDING Ions have charges to them, either they are negatively charged or positively. Due to

this fact some ions are attracted to others and form bonds, this results in and Ionic

compound with a neutral charge.

How it Works You begin with two Ion’s a metal and a non-metal. The metal will have a

positive charge and the non-metal will have a negative charge. Follow the following

instructions to make the ionic compound.

1. Write the symbol of the metal first with its charge on the top. (Lithium

ion)

Li!!

2. Next write the symbol of the non-metal with it’s charge on the top. (Oxide

ion)

Li!! O!!

3. Swap the charges and write them as subscripts, remove the positive or

negative signs.

Li!O!

4. If there is a 1 in the subscript remove it (1 is assumed) or if the subscripts

can be simplified. Simplify them.

Li!O 5. Voilà you have your Ionic Compound.

Ion+1 Ion-1 Netural

IonicCompound



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POLYATOMIC BONDING Some ions bond with each other and instead of making neutral bonds they make

charged polyatomic compounds. These compounds, their formula and charges are listed

below.

You do not have to memorize these polyatomic ions. There will be a chart similar to

this given on a test. These ions bond with other ions to become natural.

How it Works You begin with a polyatomic compound, and an Ion. The one with the positive

charge is written first and the one with the negative charge is written after.

1. Write the compound or ion that has the positive charge first and the one

with the negative charge second

Ca!! PO!!! 2. Swap the charges, remove the plus and minus signs and simplify if

possible (get ride of the 1’s as well)

Ca!(PO!)!

Polyatomic

Compound Ion+ or -

NeturalPolyatmoicCompound



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MOLECULAR COMPOUNDS Unlike how Ionic Compounds bond attracted ions, molecular compounds form when

you have two non-metals that can share electrons (something the electrons are around one

nuclei and sometimes the other). This type of bonding is also known as covalent compounds

How it worksWhen two non-metals have enough electrons to satisfy the other atom’s needs

to become stable, and there is enough energy they will bonded and share some

electrons. Consider the following example:

We have two hydrogen atoms having one valences electron, and one oxygen

atom with six valence electrons. If one hydrogen atom, and the oxygen atom were to

share one electron with each other, the hydrogen would have a complete set but the

oxygen still would need one more electron. If the oxygen shared another electron with

the other hydrogen, the hydrogen shared its electron. All the atoms would be stable

in terms of reactivity, and you would form the compound known as Dihydrogen

Monoxide, commonly called water.

1p+1p+ 8p+

8no

Two hydrogen atoms One oxygen atom (only

valence electrons drawn)

One molecule of

DiHydrogen Monoxide

8p+

8no

1p+1p+



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Types of bondsThere are three types of bonds; atoms can make in order to combine into a

compound. The bonds vary based upon the amount of electrons available and the

abundance of an atom.

Single Bond A single bond is similar to the example on the page above, where both

atoms are sharing one electron with the other (2 electrons in total). In the

case above, each hydrogen atom was sharing one electron with oxygen, and

oxygen was sharing one electron with each hydrogen atom.

Double Bond

A double bond occurs when each atom shares two of its electrons with

the other atom, making four electrons in total. This can be seen in Carbon

Dioxide, where the carbon atom, and the oxygen atoms are sharing two

electrons each to form the bond.

Triple Bond

A triple bond occurs when three pairs of electrons are shared. Usually

one shares four, and the other shares two. This can be observed in Carbon

Monoxide.

Naming the CompoundsNaming a molecular compound is fairly simple there are a set of rules and

prefixes, which have to be memorized.

1. Write the atom in the lower left of the periodic table first, followed by the

second atom.

2. Next count the number of atoms for each element.

3. Change the ending of the second element to –ide.

4. Place the appropriate prefix in front of the name.

5. If there is mono in front of the first element, remove it.

Exceptions

Some compounds have common name they are as follows:

Value Prefix

1 Mono

2 Di

3 Tri

4 Tetra

5 Penta6 Hexa

7 Hepta

CH4 - Methane

H2O2 – Hydrogen Peroxide

NH2 - Ammonia

O3 - Ozone



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Diatomic GasesDiatomic gases are gases that are always bonded, with them to form stable

gas compounds. All of the Halogens plus Hydrogen, Oxygen, and Nitrogen form

diatomic gases. You will never find just a single atom of these elements in the open.

CHEMICAL REACTIONS There are two parts of a chemical reaction, the reactants and the products. The

products the end result of the equation, and the reactants are what you start with. After each

compound in the equation you add (s) for solid, (g) for gas, (aq) for aqueous, and (l) for liquid.

There are five types of chemical reactions, theses reactions result in different products, and

start with different reactants.

DecompositionDecomposition is when you have a single compound, which breaks down into

two or more different elements.

Single ReplacementSingle replacement is where a metal or non-metal will replace another metal

or non-metal in a compound.

Double ReplacementDouble replacement is when the ions in the compounds, switch places with

each other.

Synthesis A synthesis reaction occurs when two substances form one compound.

CombustionSimilar to a synthesis reaction, except when two or more substance react to

produce an oxide and energy.

CHEMICAL EQUATIONS In order to describe a chemical reaction we can right chemical equations. You will be

given a word equation, which will be converted in chemical equations. The following steps

are used to convert a word equation into a chemical equation.

1. Write the compounds one by one, making sure of the charges.

2. Place (s), (l), (g), (aq), to indicated the state of the compound.

3. Balance each side of the equation.



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Syed Kamran CourseCentral 10

Balancing EquationsWhen balancing equations we must realize that matter cannot be made nor

destroyed. If you to have 2 atoms of Hydrogen on one side of the equation, you must

have 2 atoms of Hydrogen on the other side. Once you have written the compounds

properly you can balance the equation. Following is an example of balancing a

chemical equation.

! + ! = ! – Write all the compounds in the equations.

! + ! = 2! – We have two oxygen’s on the left side and one of the other,

so we add a two as the coefficient of H2O.

2! + ! = 2! – Now we have 4 atoms of hydrogen on the right, and two on

the left, so we can add 2 as the coefficient.

2! + ! = 2! – Now you have a balanced equation.

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Chemistry Quiz Two Notes

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