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 Student Page

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Writing in Science

Because of society relies heavily on written expression and printed material, it is important for you to posses effective writing skills.  You will be expected to:


Keep good records of all investigations and activities


Record notes from text material and lectures/discussions


Submit complete lab reports (format provided by me) following the scientific method


Scientific Method

graphical flowchart of the scientific method


Everything is made up of chemicals; you, your clothes, the soda you drank at lunch (which is now under your desk), the medicines we take, the shampoo you use, the food we eat,  and the list goes on and on. 

Chemistry is the study of all substances and the changes that they undergo.  Chemists strive  to satisfy their own curiosity by answering the questions of WHY things happen the way they do.

Measuring in Science

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Atom Builder

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Everything in our world is made of atoms, which we can visualize as negatively charged electrons orbiting rapidly around a nucleus, composed of positively charged protons and neutral neutrons.  The different types of atoms are called the chemical elements, substances that do not break down into simpler substances by chemical means.  There are 90 elements found naturally on Earth, but there are 109 presently on the periodic table of the elements. 

    Protons and neutrons have more mass than electrons, so we find an atom’s total mass using only the masses of its nuclear particles.  Hydrogen has a mass of 1.67 x 10 -24 grams, about one atomic mass unit (u).  To find an atom's mass, simply find its mass number on the periodic table. All elements have isotopes, forms of elements with different numbers of neutrons in the nucleus.  The number of protons in a nucleus, its atomic number, shows identity. If the number of protons change, then it becomes a different element. The atomic number also determines the number of electrons in a neutral atom which also determines its chemistry.



All Matter in universe is composed of Atoms

bullet Elements are composed of only 1 type of atom.
bullet Atoms have electrons which are very small, negatively charged, and have a negligible mass
bullet Electrons move in orbits around the center of the atom - in relatively distinct areas called Energy Levels.
bullet Atoms have a Nucleus which contain Protons & Neutrons.


Subatomic Particles











None / Neutral



Energy Levels / orbits




Periodic Table Notation

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Elements increase in atomic number across each period, and down each group.



Group - the columns going down.

number of valence electrons in the atom


Period - the rows going across.

number of main electron shells

Infoplease periodic table




Isotopes are atoms of the same element with different numbers of neutrons (mass). They react chemically the same as the normal form of the element and are normally radioactive.

Example Isotopes: Hydrogen

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Bohr Model

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Neutral atoms have the same number of protons and electrons.


2 electrons in the first energy shell


8 electrons in every shell afterward. (2nd shell must be filled before 3rd, and so on)


Every atom wants to be a noble gas and have a full outer shell (8 electrons).


Ions. If an atom picks up an electron (-), it becomes negatively charged; there are now more electrons than protons. If an atom loses an electron (-), it becomes positively charged; there are now more protons than electrons. Atoms with electron imbalances are called ions.

Acids. Acids in water separate into ions, and the positive ion is hydrogen (H+). When hydrochloric acid (HCl) mixes with water, it separates into positive hydrogen (H+) and negative chlorine (Cl-). Hydrogen (H+) combines with water (H2O) to make hydronium (H3O+).

Bases. Bases in water also separate into ions, and the negative ion is hydroxide (OH-). When the base sodium hydroxide (NaOH) mixes with water, it separates into positive sodium (Na+) and negative hydroxide (OH-).



Two forces hold atoms together.  The electric force, a force vastly stronger than gravity, holds an atom's electrons in the space around its nucleus.  The nuclear force holds an atom's protons and neutrons together in its nucleus.  It is the strongest known force in nature, but is effective only over a short range.

    The chemical properties of an atom depend mainly on the electrons in its outer shell or valence shell.  If this shell is full, the atoms are called inert, or non-reactive.  If it is partially filled an atom can enter a chemical reaction and form chemical bonds.  Chemical bonds bind different elements tightly together in compounds.  Both compounds and elements can exist as molecules, which are the smallest units of combined atoms with their own chemical identity. 


Chemical Bonds

When a Chemical Reaction occurs atoms gain, lose or share electrons. They always want to have their outer energy level full of electrons When an atom has a different number of protons & electrons it is called an ion. A positively charged ion has more protons than electrons A negatively charged ion has more electrons than protons.


There are four principal bonds between atoms: ionic, covalent, metallic, and hydrogen bonds.


Ionic, Covalent &  Metallic Bonds

Ionic bonds form when one atom gives up or transfers one or more electrons to another atom.  Metals are found on the left side of the periodic table (valence shells are less than half full) and  react with nonmetals which are found on the right side of the periodic table (valence shells are nearly full),  and through this bonding form ionic bonds.


Metal atoms transfer their valence electrons to nonmetal atoms. 


Ionic bonds form salts.


All ionic compounds are solid at room temperature


The force of attraction of two oppositely charged ions is very strong.

Covalent bonds form when 2 atoms share one or more electrons between them.  Nonmetals react with nonmetals through covalent bonds, in which two atoms share electrons in the region between them.  Remember the Bohr models we did in class?


Non-Polar Covalent bonds form when two atoms share electrons equally.


Polar Covalent bonds form when two atoms share electrons unequally.


Atoms can share more than 1 electron between them forming multiple bonds


A Molecule is a group of 2 or more atoms held together by covalent bonds.

Metallic Bonds hold atoms together in a metallic substance.  The van der Waals bond (Van der Waals AKA London Dispersion Force) occurs when the motions of an atom's electrons polarize it, creating positively and negatively charged regions that attract any other neutral atoms in close proximity. 


Atoms of metals are stable because they share their electron among themselves.


Metal atoms stick together with metallic bonds, in which the outermost electrons of the atoms wander freely, shared by all the connected metal atoms.  


If energy is released when bonds are formed or broken the process is exothermic


If energy is absorbed  in the chemical reaction the process is endothermic.

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A Chemical Reaction happens whenever a chemical bond is formed or broken.

Reactants are the substances existing before the reaction.  Products are the substances existing after the reaction.  Catalysts are the substances that speed up the rate of a reaction.

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Names & Symbols of Elements

Most Common Names and Symbols

Element Symbol




















Elements, Compounds & Mixtures

The Chemistry of Water

Chemical Name

Chemical Formula

Structural Formula


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Elements in the Human Body

Element Symbol Mass (%)
Oxygen O 65.0
Carbon C 18.5
Hydrogen H 9.5
Nitrogen N 3.3
Phosphorus P 1.0
Sulfur S 0.3
Sodium Na 0.2
Magnesium Mg 0.1
Silicon Si trace
Fluorine F trace

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Molecular Structure & Moles

Molecular weight is the sum of the weights of all the atoms in a molecule.

A mole (mol) is equal in number to the molecular weight of a substance, but upscaled from daltons to units of grams.


Use the periodic table to calculate to molecular weight of each atom, and then add the totals together to get the mass of the molecule.  Your answer should always contain the proper units, g/mol.

One mole of sucrose weighs 342 g.


          12 x  12 g  =  144 g/mol

22 x   ___ = ___

  11 x   ___ = ___

                   342 g/mol


1.0 M solution would have 342 g of sucrose to 1 liter of water

One mole of ethyl alcohol (C2H6O) also contains 6.022 x 1023 molecules but weighs only 46g because the molecules are smaller.

Weight vs. Mass

Weight is a force, it is the pull of Earth's gravity on an object. While weight of an object is a force, the mass measures inertia.

An object's weight changes if the pull of gravity changes, but an object's mass is the same everywhere in the universe. If air resistance were not a factor, everything near the Earth's surface falls with acceleration g, so weight = mg.



Acid & Base Systems

pH scale

 A pH below 7 indicates an acid solution; A pH above 7 indicates an alkaline (base) solution.

pH Lab

Red Cabbage Indicator


 2   4   6   8   10   12 
 Color   Red   Purple   Violet   Blue   Blue-Green   Greenish Yellow 


Acid Rain

pH Tutorial
Indicators Red Cabbage Indicator


Organic Compounds

The Chemistry of Carbon

Organic chemistry is the branch of chemistry dealing with the compounds of carbon. While it is only the fourteenth most common element on earth, carbon forms by far the greatest number of different compounds. Organic chemistry is of vital importance to the petrochemical, pharmaceutical, and textile industries, where a prime concern is the synthesis of new organic molecules and polymers.

Compounds containing only hydrogen and carbon are called hydrocarbons, the simplest is methane (CH4).

Organic Lab

Testing for organic compounds in foods

Organic Chem