Matter+and+the+Periodic+Table

Just as a side note Mr. Desjardins said to focus on the Periodic Table. Everyone might want to keep that in mind when they study for the test :) __**Chapter 2**__  Describing Matter
 * Matter and the Periodic Table****  **Thank you guys for doing such a good job getting all the information and putting it up here!**   **I hope this helps everyone with their studying, clarifying, or just review.**   **You guys did a great job and I hope you like it!**
 * 2.1-2.2 --Hannah Mullen, Nick Achin, Emily Crawford (Co-Editor)**
 * Description of matter is based on observation.
 * **Extensive Properties**: rely on the amount of matter
 * Matter has mass and takes up space
 * Mass=amount of matter in an object
 * Volume=the amount of space occupied by an object


 * **Intensive Properties**: rely on the type of matter in an object
 * Ex. Hardness,Color, Melting Point, Freezing Point....

Identifying Substances
States of Matter Physical Changes
 * Substance=Matter with a uniform and definite composition
 * Ex. Gold, copper, silver...
 * ** Physical property **: a condition that can be observed without changing the composition of a substance.
 * can help distinguish between substances.
 * Exs of Physical properties: State, Color...
 * Water exists in 3 states
 * 1) Solid or ice
 * 2) Liquid or water
 * 3) Gas or steam/vapor
 * //__Solids__//
 * **Solid** : a form of matter with a definite shape and volume
 * Does not depend on the shape of its container
 * Particles are packed tightly and orderly
 * Incompressible: difficult to squeeze into a smaller volume
 * Only expand slightly when heated
 * //__Liquids__//
 * **Liquid** : a form of matter that has an indefinite shape, flows, and has a fixed volume
 * Takes the shape of its container
 * Particles are close together, but are not rigid and orderly like in a solid
 * Almost incompressible
 * Usually expand slightly when heated
 * //__Gases__//
 * **Gas** : a form of matter that takes the shape and volume of its container
 * Particles are far apart and move quickly
 * Easily compressible
 * **Vapor** : the gaseous state of a substance that is usually a liquid or solid at room temperature
 * Not an exact synonym of gas, as the word gas is used to describe substances that are gaseous at room temperature[[image:http://www.grc.nasa.gov/WWW/k-12/airplane/Images/state.jpg width="371" height="282"]]
 * **Physical Change** : a change during which some properties of a material change, but the composition of the matter does not change
 * Ex.) melting
 * Can be reversible or irreversible
 * Reversible- all physical changes that involve change from one state to another
 * Ex.) freezing
 * Irreversible- all physical changes that cannot be undoneEx.) cutting

Classifying Mixtures
>> -Heterogenous has two or more phases. Separating Mixtures
 * **Mixture**: A physical blend of two or more non-chemically combined substances.
 * Some mixtures are recognizable like the mixture of vegetables in a salad.
 * Others can be hard to see like salt and sugar.
 * **Heterogenous Mixture**: A mixture in which the composition is not the same throughout.
 * **Homogenous Mixture**: A mixture in which the composition is the same throughout.[[image:http://bp3.blogger.com/_A1VjtzmEHds/SInqc2J5-VI/AAAAAAAABAY/rc04Ir-h_mM/s400/Filtration(1).jpg width="360" height="270" align="right"]]
 * Also known as a solution
 * **Phase**: Any part of a sample with uniform composition and properties.-Homogenous has one phase.
 * Separating mixtures can be easy or complex.
 * Sometimes you can pull the substances apart or you may have to heat or cool them.
 * **Filtration**: The separating of a solid form a liquid.Example- Pasta and water filter
 * **Distillation**: The process of boiling a liquid into a vapor that is then condensed into a liquid.
 * Water is distilled to separate the liquid from the other substances in it.

Recognizing Chemical Changes:
 * 2.3-2.4 --Darby Barrett, Brittany Chlebek, Lexie St. Jacques (Co-Editor)**
 * Possible clues to a chemical change include a transfer of energy, a change in color, the production of gas, or the formation of a precipitate
 * Every chemical change involves a of energy
 * ** Precipitate: ** a solid that forms and settles out of a liquid mixture
 * [[image:mrdesjardinsdd12wiki/precipitate.jpeg align="left"]]
 * [[image:mrdesjardinsdd12wiki/precipitate.jpeg align="left"]]

Conservation of Mass: >
 * The only way to be sure that a chemical change has taken place is to test the composition of a sample before and after the change
 * Appearances can be deceiving: never rely on appearances for an answer
 * During any chemical reaction, the mass of the products is always equal to the mass of the reactants
 * Careful measurements show that the total mass of the reactants equals the total mass of the products
 * Mass holds constant during physical changes
 * [[image:mrdesjardinsdd12wiki/law_of_conservation_of_mass.jpg]]
 * ** Law of conservation of mass: ** states that in any physical change or chemical reaction, mass is conserved
 * Mass is neither created nor destroyed
 * The conservation of mass is more easily observed when a change occurs in a closed container

Symbols and Formulas Some alchemic symbols used in earlier centuries
 * Symbols are used to represent elements
 * Formulas are used to represent formulas
 * **Jöns Jacob Berzelius:** developed an element-naming system based on the Latin names of elements
 * Elements are represented by a one- or two- letter symbol
 * First letter is ALWAYS capitalized
 * IF a second letter is used, it is lowercase


 * Symbols provide a way to write the chemical formulas of compounds
 * Subscripts indicate the relative proportions of the elements in the compound

[|The Elements' Song]

Chemical Changes: Chemical change = chemical reaction (when one or more substances change into one or more new substances)
 * ** Chemical property: **the ability of a substance to undergo a specific chemical change is called a chemical property
 * Chemical properties can be used to identify a substance
 * During a chemical change, the composition of matter always changes
 * ** Reactant: ** a substance present at the start of the reaction
 * ** Product: ** a substance produced in the reaction



[|Chemical vs. Physical Reaction Video]

**__Chapter 6__** = Searching for an Organizing Principle =
 * 6.1 --Elena Berube. Kyle St. Pierre (Co-Editor)**


 * There were a few elements that were known for a long time, but only 13 had been identified by 1700
 * Chemist suspected that others existed and had given names for them, but they could not isolate the elements format he compounds
 * With the use of scientific method, more and more elements would be discovered
 * Chemists organized the elements into groups based upon their specific properties
 * J.W. Dobereiner published a classification system that organized the elements into triads
 * Although the elements grouped together do not look alike, they have similar chemical properties
 * In the triads, he noticed that one of the elements tended to have properties with values that fell midway between those of the other two elements
 * The one problem with this system is that not all of the elements could be grouped onto triads

Example:



= Mendeleev's Periodic Table =
 * Many attempts to create a good way of organizing the elements
 * Mendeleev published a table, arranged based on a set of repeating properties
 * Method for arranging the elements was placing them in order by atomic mass



Dmitri Mendeleev
 * Two question marks between the entries for zinc and arsenic
 * Mendeleev did this because he knew that bromine belonged with chlorine and iodine
 * He predicted that elements would be discovered to fill those spaces, and predicted what their properties would be based on their locations in the table
 * In 1875 and 1886, elements that belonged in the empty spaces on his table were discovered
 * There was a very close match between Mendeleev's predicted properties and the actual properties of the elements
 * This match convinced scientists that Mendeleev’s periodic table was a powerful tool.

The Periodic Law
Notice that the elements are arranged in increasing order of atomic number from left to right. Hydrogen is first and it's atomic number is 1, Helium is second and it's atomic number is 2, and so on.
 * The atomic mass of Iodine is 126.90 and the atomic mass of Tellurium is 127.60.
 * Mendeleev thought that their atomic masses were incorrect, so he placed Tellurium before Iodine on his table
 * Even though Iodine has a smaller mass than Tellurium, it was later discovered that Menedleev's placement was correct.
 * British physicist Henry Moseley determined an atomic number for each known element based on their number of protons. Tellurium's atomic number is 52 and Iodine's is 53, which proved Mendeleev's placement was correct and that it made sense for iodine to come after tellurium on the table.
 * In the modern periodic table, elements are arranged in order of increasing atomic number.


 * 6.1 --Lauren Berube, John Bailey (Co-Editor)**
 * The Periodic Table of Elements **
 * Almost all are arranged the same way
 * Made of Periods
 * 6 and 7 place below to make table more compact
 * United States scientists use labes like 1A and 2B to mark vertical columns of table
 * International Union of Pure and Applied Chemistry: organization that sets standard for chemistry
 * recently labeled table with numbers 1 through 18 across vertical columns
 * Elements can be grouped into 3 classes based on their properties
 * 1) ** Metals **
 * 2) ** Nonmetals **
 * 3) ** Metalloids **
 * Metals
 * 80% of table
 * Good conductors of heat and electric current
 * High luster
 * Caused by the metal’s ability to reflect light
 * All, except mercury, are solid at room temperature
 * Ductile and malleable
 * Nonmetals
 * Most are gases at room temperature
 * nitrogen and oxygen
 * Some solids
 * sulfur and phosphorus
 * Only on liquid
 * bromine
 * Variation makes general description difficult
 * Poor conductors of electricity
 * carbon is exception
 * Solids tend to be brittle
 * Metalloids
 * Have properties of metals and nonmetals
 * depends on conditions


 * 6.2 --Sam Massoud, Melanie Brondyk (Co-Editor)**
 * Classifying the Elements **

Example:
 * Squares in the Periodic Table
 * The periodic table displays the symbols and names of the elements
 * information about the structure of their atoms.
 * The color that the element symbol is printed in represents the element's state at room temperature:
 * **Black** = solid
 * ** Red ** = gas
 * **Blue** = liquid
 * **Grey** = not found in nature
 * The background colors in the squares distinguish the elements groups
 * Orange = **alkali metals** and Yellow = **alkali earth metals**
 * alkali metals are in group 1A
 * alkali earth metals are in 2A
 * Green = **halogens** in group 7A

//Note: the colors represented in the wiki and on this periodic table are not the same as the table on pages 162 and 163 in the textbook.//

=** Electron Configurations in Groups **=
 * Electrons have key role
 * Elements can be a noble gas, a representative element, a transition metal, or a inner transition metal
 * Where they’re sorted is based on electron configurations
 * ** The Noble Gases **
 * Ex.) Helium
 * Elements in group 8A
 * Nonmetals
 * Also known as inert gases because barely take place in reactions
 * **The Representative Elements**
 * Groups 1A through 7A
 * Display wide range of physical and chemical properties
 * Metals/nonmetals/metalloids
 * Most solids
 * Its group number equals number of electrons in the highest occupied energy level

** Transition Elements **

 * Elements in the B groups, which provide connection between the two sets of representative elements
 * Two types: transition metals and inner transition metals
 * **Transition metals** : group B elements that are shown in main body of periodic table
 * Ex.) copper, silver, gold, and iron
 * Atoms are highest occupied s sublevel and a nearby d sublevel contain electrons
 * Characterized by amount of electrons in d orbitals
 * **Inner transition metals** : below main body of the periodic table
 * Atoms are the highest occupied s sublevel and a nearby f sublevel generally contain electrons
 * **Blocks of Elements**
 * The s block contains elements in Groups 1A and 2A and the noble gas helium
 * The p block contains elements in Groups 3A, 4A, 5A, 6A, 7A, and 8A (no helium)
 * The d block contains the transition metals
 * The f block contains the inner transition metals
 * Each period match to a principal energy level



**Trends in Atomic Size** **Group Trends in Atomic Size** **Periodic Trends in Atomic Size**
 * 6.3 --Sean Lydon, Kyle Mahoney (Co-Editor)**
 * In general, atomic size increases from top to bottom in a group and decreases from left to right across a period
 * One way to think about atomic size is to look at the units that form when atoms of the same element join to make molecules
 * Because atoms in the molecule are identical, distance between the nuclei of these atoms can be used to estimate the size of the atoms, expressed as an atomic radius
 * **Atomic radius:** one half of the distance between the nuclei of two atoms of the same element when the atoms are joined
 * Very small, so they are usually measured in picometers (1 picometer is 1 trillionth of a meter)
 * Example: the distance between the nuclei of an iodine molecule is 280 pm. Atomic radius is one half of that distance, so the atomic radius of an iodine atom is 140 pm.
 * Atomic radius is on the vertical plane and atomic number is on the horizontal plane
 * The atomic radius of the alkali metals (yellow circles) and the noble gases (blue circles) increases as the atomic number increases
 * Increase is known as a trend
 * As the atomic number increases in a group, the charge on the nucleus increases and the number of occupied energy levels increases
 * Affect atomic sizes in contradicting ways
 * Increase in positive charge attracts electrons to the nucleus
 * The increase in occupied orbitals stops electrons in the highest occupied energy level from being drawn to protons in the nucleus
 * The effect of the increase in nuclear charge is not as great as the effect of stopping electrons from being attracted by protons
 * Therefore, the atomic size increases.
 * In graph of atomic sizes, atomic size decreases across a period from left to right
 * Each element has one more proton and electron than the element before it
 * Across a period, electrons are added to the same energy level and the shielding effect (when electrons are stopped from being attracted by protons in the nucleus) is constant for all the elements in a period
 * The increasing nuclear charge draws the electrons in the highest occupied energy level closer to the nucleus and so the atomic size decreases

=Ions =
 * Some compounds are composed of particles called ions.
 * **Ion **: an atom or group of atoms that have a positive or negative charge.
 * Regular atoms are electrically neutral because they have equal numbers of protons and elcectrons.
 * <span style="color: #000000; font-family: Arial,Helvetica,sans-serif;">Ions become charged when they lose or gain one or more electrons from their outermost energy levels.
 * <span style="font-family: Arial,Helvetica,sans-serif;">Positive and negative ions form when electrons are transferred between atoms.
 * <span style="color: #000000; font-family: Arial,Helvetica,sans-serif;">Atoms of metallic elements form ions by losing one or more electrons from their highest occupied energy levels
 * Atoms of nonmetallic elements form ions by gaining one or more electrons
 * If you have an atom with less electrons than protons, it's a positive ion
 * If it has less protons than electrons it is negatively charged

__**// Ions with a positive charge are called cations. Ions with a negative charge are called anions. //**__


 * 6.3 -Maddie Harmon, Ellen Mahoney (Co-Editor)**
 * Table 6.1**
 * Ionization Energies of First 20 Elements (kJ/mol)**



**Trends in Ionization Energy** Here's a link for a video that explains ionization energy more: []
 * Look at Table 6.1**
 * Look at lithium (Li), sodium (Na), and potassium (K)
 * Ø Increase in energy between 1st and 2nd ionization energies is large
 * Relatively easy to remove 1 electron from Group 1A metal atom, but difficult to remove 2ndelectron
 * Ø Group 1A metals form ions with 1+ charge
 * Elements can move to higher energy levels when atoms absorb energy
 * Sometimes there’s enough energy to overcome attraction of protons in nucleus
 * ** Ionization energy -**energy required to remove an electron from an atom
 * Ø Measured when an element is in its gaseous state
 * **First ionization energy** - energy required to remove 1stelectron from an atom
 * Ø Cation produced has 1+ charge
 * First ionization energy tends to decrease from top to bottom within a group and increase from left to right across a period
 * **Second ionization energy** - energy required to remove an electron from an ion with a 1+ charge
 * Ø Ion produced has 2+ charge
 * ** Third ionization energy **- energy required to remove an electron from an ion with a 2+ charge
 * Ø Ion produced has 3+ charge


 * The nuclear charge has less of an effect on the electrons in the highest occupied energy level as the atom size increases.
 * Less energy is needed to remove an electron from this energy level and the first ionization energy

**Periodic Trends in Ionization Energy**

 * The first ionization energy of representative elements tends to increase from left to right across the periodic table
 * The nuclear charge can explain this trend.
 * It increases across the period, but the shileding effect remains the same.
 * Therefore, there is an increase in the attraction of the nucleus for a electron.
 * Which shows that it takes more energy to remove electrons from atoms.

Here's a video to futher explainperiodic trends in ionization energy. []

= ** Trends in Electronegativity ** =
 * 6.3 --Joe Jennings, Korey Dufault (Co-Editor)**


 * ** Electronegativity :** is the ability of an atom of an element to attract electrons when the atom is in a compound.


 * The elements are arranged in the same order as in a periodic table.
 * The noble gases are omitted because they do not form many compounds.
 * The data in Table 6.2 is expressed in units called Paulings.
 * Linus Pauling won a Nobel Prize in Chemistry for his work on chemical bonds. He was the first to define electronegativity
 * In general, electronegativity values decrease from the top to bottom within a group.
 * For representative elements, the values tend to increase from left to right across a period.
 * Metals at the far left of the periodic table have low values.
 * By contrast, nonmetals at the far right (excluding noble gases) have high values.
 * The electronegativity values among the transition metals metals are not as regular.
 * The least electronegative element is cesium, with an electronegativity value of 0.7.
 * It has the least tendency to attract electrons.
 * When it reacts, it tends to lose electrons and form positive ions.
 * The most electronegative element is fluorine, with a value of 4.0
 * Because fluorine 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.

Here is video to help you with your understanding of electronegativity:

media type="youtube" key="ijc94QMhEQE" height="315" width="560"


 * Trends of electronegativity van be observed with periodic table
 * Elements on bottom left of periodic table have lowest amount of electronegativity
 * Elements on top right have most electronegativity