Editor: Phillip Royal
Coeditors: Katie West, Delia Calderon, Frank Morley, Abbey Salvas, Siri Devlin, Kerry Desmond, Nic Cunha, Randy Melanson


First developed by Dmitri Mendeleev in 1869, the periodic table has proved to be one of best means of arranging the elements, by increasing atomic number. The table is studded with all 118 elements known to man, and continues to grow in size with each progressive discovery. This unit is also about the interaction of elements between each other, in the formation of mixtures and solutions while also discussing the properties of elemental groups. In addition to this, the trends found in atomic size, ionization energy and electronegativity in certain groupings of the periodic table are observed.

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2.1 Properties of Matter

Kati West (pg. 39-43)
Describing Matter

Extensive Properties

matter – anything that has mass and takes up space

mass – measure of amount of matter in an object

volume – a measure of the space occupied by an object

extensive property – a property that depends on the amount of matter in a sample

ex: mass and volume

Identifying Substances

substance – the uniform and definite composition of matter

physical property – a quality or condition of a substance that can be observed or measured without changing the substance’s composition

ex: hardness, color, conductivity, malleability

States of Matter

solid – form of matter with definite composition of matter

particles are packed tightly together

it is difficult to squeeze a solid into a smaller volume

expands only slightly when heated

liquid – form of matter that has indefinite shape but definite volume

almost incompressible

expands slightly when heated

gas – form of matter that has indefinite shape and volume

particles are very far apart, easily compressed to a smaller volume

vapor – the gaseous state of a substance that is liquid or solid at room temperature

Physical Changes

Physical change – some properties of a material change, but composition doesn’t

Split into reversible and irreversible changes

2.2 Mixtures

Austin Burlone (pg. 44-47)

vClassifying Mixtures
  • Mixtures are physical blends of two or more components
    • Some mixtures easier to recognize than others
    • Based on distribution of their components, mixtures can be classified as heterogeneous or as homogenous mixtures
vHeterogeneous Mixtures
  • Components are not evenly distributed throughout mixture
  • Composition is not uniform throughout
vHomogenous Mixture
  • Mixtures in which the composition is uniform throughout
  • Also called solutions
    • Many solutions are liquids
    • Yet some can be gases (air) or solids (stainless steel)
    • Phase: any part of a sample with uniform composition and properties
      • Homogeneous consists of one phase
      • Heterogeneous consists of two phases
vSeparating Mixtures
  • Many mixtures are not easy to separate
  • Differences in physical properties are used to separate mixtures
  • Process that separates a solid from a liquid in a heterogeneous mixture is called filtration
  • Example: Colander allows water to pass through holes but not pasta
  • Process where a liquid is boiled to produce a vapor that is then condensed into a liquid
  • Example: Tap water is heated which causes water vapor to rise out of it into a glass tube. Glass tube is surrounded by cold water which turns the vapor back into liquid which is gathered in a different flask.

2.3 Elements and Compounds

Elaney Marcotte (pg. 48-52)

Distinguishing Elements and Compounds

  • Substances can be compounds or elements.
  • Element: the simplest form of matter that has a unique set of properties
  • An example of an element is oxygen and hydrogen
  • Compound: a substance that contains two or more elements chemically combined in a fixed proportion
  • An example of a compound is water
  • Compounds can be broken down into simple substances, but elements cannot

Breaking Down Compounds

  • Physical methods cannot be used to break down a compound
  • A chemical change is necessary to break apart a compound
  • Chemical Change: A change that produces matter with a different composition then the original matter
  • Heat and electricity can be used to break apart a compound
  • Elements cannot be broken down with chemical changes

Properties of Compounds

  • The properties of elements and compounds are very different
  • Sugar is a white solid that is sweet, carbon is a black tasteless solid
  • Hydrogen is a gas that burns with oxygen which is colorless
    • This creates water which can stop burning
  • When sodium and chlorine chemically combine, they change properties and their composition
  • Sodium is a soft grey metal and chlorine is a green-yellow poisonous gas
    • Sodium chloride is a white solid

Distinguishing Substances and Mixtures

  • It is hard to decide if matter is a substance or mixture based on appearance
  • Homogeneous mixtures and substances are made up of one kind of matter
  • You can use characteristics to distinguish mixtures from substances
  • Substance: if the composition of matter is fixed
  • Mixture: if the composition of a material may vary

Symbols and Formulas

  • Chemists use symbols to represent elements, and formulas to represent compounds
  • Some symbols were used in earlier centuries
  • The symbols today are based on a system developed by Jöns Jacob Berzelius
  • His symbols were based on Latin names for the elements
  • Chemical Symbol: a one- or two- letter representation of an element
  • The first letter is always capitalized and the second is always lowercase
  • If the English and Latin names are similar, then the symbol will be from the English name
  • Examples include Ca for Calcium, S for Sulfur, and O for Oxygen
  • Chemical symbols allow for an easy way to write chemical formulas for compounds
  • H, O, and C are the symbols for Hydrogen, Oxygen, and Carbon
  • H2O is the formula for water
  • Subscripts in chemical formulas are used to show the relative proportions of the element in the compound
  • The subscript 2 in H2O shows that there are two parts oxygen to each part oxygen
  • The formula for a compound is always the same

Symbols for Latin Names for Some Elements
Latin Name

2.4 Chemical Reactions

Delia Calderon (pg. 53-55)
Chemical Changes
  • Burning, rust, rot, decomposition, fermentations, explosions, and corrosion are all form of chemical change.
  • Chemical property- the ability of a substance to undergo a specific chemical change
  • Chemical properties can be used to identify a substance, but can be observed only when a substance undergoes a chemical change.
  • During a physical change, the composition of matter never changes; the substances present before a change are the same substances present after the change.
  • During a chemical change, the composition of matter always changes
  • Chemical change is also called a chemical reaction, one or more substances change intone or more new substances during a reaction.
  • Reactant- the substance present at the start of the reaction
  • Product- a substance produced in the reaction

Recognizing Chemical Changes
  • Possible clues to a chemical change include a transfer of energy, a change in color, the production of a gas, or the formation of a precipitate.
  • Transfer of energy may be the energy given off by the stove to form heat and light that cooks food.
  • Food turning brown as it cook is another clue of an ongoing change,
  • Ring of soap scum formed around a bathtub is a precipitate, a solid that forms and settles out of a liquid mixture.
  • If you observe a clue to chemical change you cannot be certain that a chemical change has taken place, it can be a result of physical change.
  • The only way to be sure that a chemical change has occurred is to test the composition of the matter before and after the change.

Conservation of Mass
  • During a chemical reaction the mass if the products is always equal to the mass of the reactants
  • Some reactions seem to involve a reduction in the amount of matter like wood afterburning, but careful measurements consider the mass of gases released in the air (carbon dioxide and water vapor) and the masses of the reactants and products equal.
  • Mass holds constant during physical changes.
  • The Law of the Conservation of Mass states that in any physical change of chemical reaction mass is conserved
  • Mass is neither created nor destroyed.
6.1 Organizing the Elements
Brett Chatfield (pg. 155)
Connecting to Your World

- In 1917 a grocery store Memphis Tennessee organized their goods for their customers instead of having the clerk gather them for the customers
- We all know that products are organized by their characteristics
- Here, you will learn that elements are organized in the periodic table similarly to how we group things in our everyday lives

Searching For and Organizing Principle

- Few elements have been known for thousands of years, including copper, silver, and gold
- Only 13 elements had been identified by the year 1700
- Chemists suspected though, that many other elements existed
- As chemists began to use scientific methods to search for elements, the numbers of elements discovered skyrocketed
- In one decade (1765-1775) chemists identified five new elements, including three colorless gases – hydrogen, nitrogen, and oxygen
- Chemists used the properties of elements to sort them into groups
- IN 1829 a German chemist J.W. Dobereiner (1780-1849) published a classification system
- In the system, elements were grouped into triads
- A triad is a set of three elements grouped together by similar properties
- Chlorine, bromine, and iodine may look different but they have a similar chemical characteristics
- He saw that they reacted well with certain types of metals
- He guessed the atomic masses of elements
- Unfortunately, not all elements that had been discovered at the time could be organized into triads

Help With Triads…

Randy Melanson(pg. 156-157)

Frank Morley (pg.158)
Metals, Nonmetals, and Metalloids
-The Periodic table shows the underlying structure of each individual element.
- By seeing where it is on the table you may know what type of element it is.
- This system was developed in 1985 by The International Union of Pure and Applied Chemistry (IUPAC)
- Their system numbered the periodic table into groups 1- 18 left to right.
- Across a period the elements go from metallic to nonmetallic
- In figure 6.5 on page 158 all of the elements in yellow are metals
- Around 80%of all elements are metals.
- Properties of Metal:
- Conductors of heat and electricity
- Has the ability to reflect light which causes it to have high luster or sheen.
- Always solid at room temperature (except Mercury)
- Many metals are ductile (can be drawn into wires)
- Ex:Copper is very ductile and second only to silver as a conductor of electricity, which is why it is often used in wires.
- Most metals are malleable (can be hammered into thin sheets)
- Ex: Aluminum can be made into very thin sheets of aluminum foil.
- Different properties of metal can determine how they are used

external image lightning.JPG

Marissa Chura (pg.159)
-these elements located in upper right section of periodic table
-most are gases at room temperature
-some are solids (sulfur, phosphorus)
-bromine-dark red liquid
General properties of nonmetals:
-not metal
-normally poor conductors of heat and electricity (carbon is an exception to this)
-usually brittle as solids
-found on the border between metals and nonmetals in the periodic table
-similar properties to metals and nonmetals
-whether it behaves as a metal or nonmetal depends on the conditions
-behavior can be controlled by changing conditions
EXAMPLE: Pure silicon=poor conductor of electricity (like nonmetals)
Silicon mixed with boron= good conductor of electricity (like metals)

6.2 Classifying the Elements

Dan Lynch (161-163)
Abbey Salvas (164-167)

Dan Lynch (pg. 161-163)

Squares in the Periodic Table

-The periodic table displays the symbols and names of the elements, along with information about the structure of their atoms.

external image boron2.gif

-On the period table, each square represents an element
-In the center of the square is the symbol, B for Boron
-Also shown is the Atomic Mass 10.81
- The name is printed under the symbol
-Also shown sometimes is the electrons in each energy level which would be shown as a vertical column
-THe symbol of Boron and many other elements are printed in black because it is a solid at room temperature.
-The symbol for bromine and mercury which are liquid at room temperature are printed in blue.
-Elements with green symbols are not found in nature
-The symbol for gases are Red
-The background color for elements in their squares are used to distinguish groups of elements.
- For example, two shades of gold are used for the metals in Groups 1A and 2A.
-Group 1A metals are called alkali metals and group 2A are called alkaline earth metals
-Some of the non-metals also have special names like 7A is Halogens.


Below is a great link with an interactive table. You can click the element, and it will show a picture of it, and describe everything about it in great detail.
I couldn't really figure out a way to get it into this wiki, but use the link it is great.

Abbey Salvas (pg. 164-167)

Electron Configurations in Groups

-electrons play a key role in determining the properties of elements
-elements can be sorted into noble gases, representative elements, transition metals, or inner transitions metals based on electron configurations

The Noble Gases

-elements in Group 8A of the periodic table
-sometimes called inert gases because they rarely take part in a reaction
-the following table shows the electronic configuration of the noble gases
-the highest occupied sublevels are the s and p sublevels; they are completely filled with electrons

The Representative Elements

-the portion of the periodic table containing Groups 1A through 7A
-display a wide range of physical and chemical properties
-some are metals, some are nonmetals, some are metalloids
-most solids, some gases, one (bromine) liquid at room temperature
-in atoms of representative elements, s and p sublevels of the highest occupied energy level are not filled
-in group 1A elements, there is only one electron at the highest occupied energy level; in the s sublevel
-in group 4A elements there are 4 electrons in the highest occupied energy level
-for any representative element, its group number equals the number of electrons in the highest occupied energy level

Transition Elements

-elements in the B groups, which provide a connection between the two sets of representative elements, are referred to as transition elements
-two types: transition metals and inner transition metals; classified based on electron configurations
-transition metals are the Group B elements that are usually displayed in the main body of a periodic table
-copper, silver, gold and iron are transition metals
-in atoms of a transition metal, the highest occupied s sublevel and a nearly d sublevel contain electrons
-these elements are characterized by the presence of electrons in d orbitals
-inner transition metals appear below the main body of the periodic table
-in atoms of an inner transition metal, the highest occupied s sublevel and a nearly f sublevel generally contain electrons
-characterized by f orbitals that contain electrons

Blocks of Elements

-if you consider both the electron configurations and the positions of the elements in the periodic table, another pattern emerges
-the periodic table is divided into blocks that correspond the to the highest occupied sublevels
-the s block contains the elements in Groups 1A and 2A and the noble gas helium
-the p block contains the elements in groups 3A, 4A, 5A, 6A, 7A, and 8A, with the exception of helium
-transition metals belong to the d block
-inner transition metals belong to the f block


-you can use this to help determine electron configurations of elements
-each period on the periodic table corresponds to a principal energy level
-s and p sublevels in energy levels 1 and 2 are filled with electrons
-for transition elements, electrons are added to a d sublevel with a principal energy level that is one less than the period number
-for inner transition metals, the principal energy level of the f sublevel is two less than the period number
-this procedure gives correct electron configurations for most atoms

6.3 Periodic Trends

Trends in Atomic Size
Co-editor: Siri Devlin Page 170 -Trends in Atomic Size-
A molecule is a neutral group of atoms joined together by covalent bonds
  • Because the atoms in each molecule are identical, the distance between the nuclei of these atoms can be used to estimate the size of these atoms- this size is expressed as an atomic radius
The atomic radius is one half of the distance between the nuclei of two atoms of the same element when the atoms are joined
  • Because the distances between atoms in a molecule are extremely small, atomic radius is measured in picometers
A picometer is one trillionth of a meter (1012 picometers in a meter)
In general, atomic size increases from top to bottom within a group and decreases from left to right across a period

Ben Ross (pg. 171)
Group Trends in Atomic Size
The atomic radius in this graph shows a trend


Trend - A general tendency or inclination

Generally, each element has one more electron and proton than the element before it does

As the atomic number increases, the change on the nucleus and its occupied energy also increases

- Atomic size usually decreases from left to right on the table

As the atomic pull increases, the atomic size decreases

The "shielding effect" of electrons on the shell is constant on all elements

An increase in positive energy draws electrons closer to the nucleus

An increase in positive energy pulls electrons away from the nucleus

Kerry Desmond (pg. 173)

I) Electrons can move to higher energy levels when atoms aborb energy

a) sometimes there is enough energy to overcome the attraction of the protons in the nucleus

b) The energy required to remobe an electron from an atom is called ionization energy.

-this energy can only be measured when an element is in a gaseous state.

-the energy needed to remove the first electron from an atom is called the first ionization energy.

-first ionization energy tends to decrease from top to bottom within a group and increase from left to right across a period.

-second ionization is the energy required to remove an electron with a 1+ charge; the ion produced will have a 2+ charge.

-third ionizationis the energy required to remove an electron from an ion with a 2+ charge; the ion produced will have a 3+ charge.

-ionization energy can help predict what elements will form

-the increase in energy between the first and second ionization energy is large

For help with the concept of ionization energy, consult this video: Video on Ionization Energy

Brendan Morrissey (pg. 174)
Trends in Ionization Energy
  • Electrons can move to higher energy levels when atoms absorb energy.
  • Sometimes there is enough energy to overcome the attraction of the protons in the nucleus.
  • The energy required to remove an electron from an atom is called ionization energy.
    • This energy is measured when the element is in its gaseous state.
    • The energy required to remove the first electron from an atom is called the first ionization energy.
      • The cation produced has a 1+ charge.
      • First ionization energy tends to decrease from top to bottom within a group and increase from left to right across a period.
    • The second ionization energy is the energy required to remove an electron from an ion with a 1+ charge. The ion produced has a 2+ charge.
    • The third ionization energy is the energy required to remove an electron from an ion with a 2+ charge. The ion produced has a 3+ charge.
  • Ionization energy can help you predict what ions elements will form.
  • The increase in energy between the first and second ionization energies is large.
  • It is easy to remove an electron from a Group 1A metal atom, but it is difficult to remove a second electron.
  • Group 1A metals tend to form ions with a 1+ charge.

Nic Cunha & Chris Hart (pgs. 177-178)
Trends in Electronegativity

In chapters 7 and 8 you will study 2 different bonds both of which electrons are involved in. Electronegativity is a property that can predict the type of bond that will be formed during a reaction. Electronegativity is the ability of an atom of an element to attract electrons when the atom is in a compound. Scientists use ionization energy to calculate values for electronegativity.
The table bellows show the electronegativity levels for all of the elements in the periodic table (ex. Lithium-Li = 1.0) Noble gasses are omitted because they form no compounds. The units of the levels of electronegativity are called Paulings, after Linus Pauling who first discovered electronegativity.
In general, electronegativity values decrease from top to bottom within a group. For representative elements, the values tend to increase from left to right across a period. Metals at far left have low values, nonmetals (excluding noble gasses) have higher values. The values for transition metals are not as regular.
The least electronegative element is cesium-----0.7. It has the least tendency to attract electrons. When reacting it tends to lose electrons and form positive ions. The most electronegative element is fluorine------4.0. Because it has such a strong tendency to attract electrons, when it is bonded to any other element it either attracts the shared electrons or forms a negative ion.

Summary of Trends
For groups 1A through 8A: Atomic size, Ionization energy, Electronegativity, and Nuclear charge levels increase from left to right across a period. Shielding is constant. Atomic size, Ionic size, Nuclear Charge, and Shielding levels increase from top to bottom. Ionization and Electronegativity decreases from top to bottom. For chart see page 178 in text book. The trends that exist among these properties can be explained by variations in atomic structure. The increase of nuclear charge within groups and across periods explains many trends. Within groups, the increase in shielding has a significant effect.