chemistry. mav marks 1/4/12 sci.html sci.html element challenge

Chemistry

Mav Marks 1/4/12

http://www.sciencespot.net/Pages/startersphysci.html

Element Challenge 1

Mav Marks 1/5/12


Element Challenge 2

Mav Marks 1/6/12


Element Challenge 3

Mav Marks 1/9/12


Atomic Math 1

Mav Marks 1/10/12


Atomic Math 2

Mav Marks 1/11/12


Atomic Math 3

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Atomic Math 4

Mav Marks 1/13/12


Common Compound 1

Mav Marks 1/17/12


Common Compounds 2

Mav Marks 1/18/12


Compound Challenge 1

Mav Marks 1/19/12



Mav Marks 1/20/12



Mav Marks 1/23/12



Mav Marks 1/24/12



Mav Marks 1/25/12


Periodic Table 1

Mav Mark 1/26/12

Test Day Take out a sheet of paper and a pencil. Clear your desk.

Physical Properties

Properties of matter that can be observed or measured without changing the identity of the matter Ex.

Color, Smell, Mass, Volume, Density Conductivity (ability to transfer energy) State {physical form (solid, liquid, gas)} Malleability (ability to be hammered into thin sheets) Ductility (ability to be drawn into a wire) Solubility (ability to dissolve in another substance)

Chemical Properties Properties

Chemical Properties: describe a substance based on its ability to change into a new substance with different properties Ex. Flammability, reactivity Metal reacts with oxygen to form rust.

Physical Properties

Properties of matter that can be observed or measured without changing the identity of the matter Ex.

Color, Smell, Mass, Volume, Density Conductivity (ability to transfer energy) State {physical form (solid, liquid, gas)} Malleability (ability to be hammered into thin sheets) Ductility (ability to be drawn into a wire) Solubility (ability to dissolve in another substance)

Physical changes A change that affects one

or more physical properties of a substance, but doesn’t change its chemical identity. Ex: breaking a pencil,

melting, dissolving sugar in water, cutting your hair, crushing an aluminum can

Physical changes An easy way to tell if something is

a physical change, is to determine if it can be undone.

Ex: Ice cubes that melt in a bowl can be

refrozen. A broken pencil still writes. Hair doesn’t turn into something else

when it’s cut.

Chemical Change A change that occurs when

one or more substances are changed into entirely new substances with different physical properties.

Ex. Baking a cake, effervescent tablets fizzing in water, a car rusting

States of Matter There are four states of matter:

solid, liquid, gas, and plasma Matter is in constant motion.

Pure Substance Pure substances are made of only one type of

particle. Elements: A pure substance that cannot be

separated into simpler substances by physical or chemical means. Ex. Carbon (C), Oxygen (O), Gold (Au) Represented by 1 or 2 letters, first letter always capital Each element has unique physical and chemical

properties that can be used to identify them. For the most part…elements can be divided into three

categories.

Pure substances: Elements

Elements

Metals Nonmetals Metalloids

Pure substances: Elements

Metals: Shiny, good conductors of electricity, malleable, ductile Ex. Iron, Copper

Nonmetals: Dull, poor conductors of electricity, brittle and unmalleable Ex. Sulfur, Neon

Metalloids: Semiconductors of electricity, somewhat malleable and ductile, some shiny some dull Ex. Boron, Silicon

Periodic Table

Pure Substance: Compounds Compounds: A pure substance that is composed

of two or more elements that are chemical combined.

Have a fixed ratio of elements. When compounds form they take on new

characteristics. Ex. Na + Cl → NaCl or 2H2 + O2 → 2H2O

Common Compounds

NaCl: Sodium Chloride (Table Salt) H2O: Dihydrogen Monoxide (Water) CO2: Carbon Dioxide CH4: Methane C6H12O6: Glucose (Sugar)

Pure Substance: Compounds

Since compounds are composed of elements that are chemical combined, they must undergo chemical changes to be broken down into the constituent elements.

Most of the substances that we deal with everyday are compounds, because most elements are too reactive to remain as a single element.

Ex: Proteins, CO2, NH4

Mixtures

A mixture is a combination of two or more substances that are NOT chemically combined. Ex. Pizza, Salt water

Mixtures can be separated by physical means. (filtration, centrifuge, evaporation, mechanical separation, magnetism)

Do not have fixed ratios.

Mixtures :Solutions Homogenous (solution): Particles are

uniform throughout Examples: Salt water, alloy (metals dissolved in

metals) Brass=zinc+copper Solute: substance that is dissolved

Ex: Salt Solvent: substances that is doing the dissolving

Ex. Water (Universal Solvent!)

Mixtures :Solutions

Solubility: basically how much of the solute can be completely dissolved by the solvent Increases with:

Temperature (except with gases) Surface Area Stirring

Atoms

An atom is the smallest particle into which an element can be divided and still be the same substance. (Building block of matter)

Composed of… Protons Neutrons Electrons

Atoms

Particle Charge Mass Location

Proton (+) 1 amu Nucleus

Neutron Neutral 1 amu Nucleus

Electron (-) Almost zero Electron Cloud

Atoms Atomic number: tells the number of protons Mass number: # protons + # neutrons Atomic mass: average of the masses of the

existing isotopes in an element Isotopes: Elements that have the same # of

protons, but a different # of neutrons Some isotopes are radioactive (carbon dating) Naming: Isotopes are named for the element and

then the atomic mass (Carbon-14)

Practice

Determine the number of protons, neutrons, and electrons in the following: Potassium (K) Oxygen (O) Sodium (Na) Helium-3 (3He)

Ions

Atoms that have either gained or lost one or more electrons. Therefore they have either a positive or negative charge. Cation: (+) Positive charge Anion: (-) Negative charge

Atoms: Electrons

Electrons orbit the nucleus of the atom. For the Bohr model electrons are placed in orbitals

by the formula 2n2, where n=energy level So for the first energy level: 2(1)2=2 The second energy level: 2(2)2=8 The third energy level: 2(3)2=18

Reactivity

All elements want to achieve noble gas configuration.

They will donate or accept electrons to achieve this configuration.

The most reactive elements are very close to achieving noble gas configuration and they readily achieve it!

Ideally they want 8 electrons in their outer shell! Valance Electrons: outer electrons

The Periodic Table

Why is the Periodic Table important to me?

The periodic table is the most useful tool to a chemist.

You get to use it on every test.

It organizes lots of information about all the known elements.

Pre-Periodic Table Chemistry …

…was a mess!!! No organization of

elements. Imagine going to a

grocery store with no organization!!

Difficult to find information.

Chemistry didn’t make sense.

Dmitri Mendeleev: Father of the Table

HOW HIS WORKED… Put elements in rows

by increasing atomic weight.

Put elements in columns by the way they reacted.

SOME PROBLEMS… He left blank spaces for

what he said were undiscovered elements. (Turned out he was right!)

He broke the pattern of increasing atomic weight to keep similar reacting elements together.

The Current Periodic Table

Mendeleev wasn’t too far off. Now the elements are put in rows by

increasing ATOMIC NUMBER!! The horizontal rows are called periods and

are labeled from 1 to 7. Periods tell the number of energy levels the atom has.

The vertical columns are called groups are labeled from 1 to 18.

Groups…Here’s Where the Periodic Table Gets Useful!!

Elements in the same group have similar chemical and physical properties!!

(Mendeleev did that on purpose.)

Why??• They have the same

number of valence electrons.

• They will form the same kinds of ions.

Families on the Periodic Table

Columns are also grouped into families or groups.

Families may be one column, or several columns put together.

Families have names rather than numbers. (Just like your family has a common last name.)

Hydrogen

Hydrogen belongs to a family of its own.

Hydrogen is a diatomic, reactive gas. (Br, I, N, Cl, H, O, F)

Hydrogen was involved in the explosion of the Hindenberg.

Hydrogen is promising as an alternative fuel source for automobiles

Alkali Metals

1st column on the periodic table (Group 1) not including hydrogen.

Very reactive metals, always combined with something else in nature (like in salt).

Soft enough to cut with a butter knife

1 electron in outer orbital

Alkaline Earth Metals Second column on the

periodic table. (Group 2) Reactive metals that are

usually combined with nonmetals in nature.

Not as reactive as alkali metals.

Several of these elements are important mineral nutrients (such as Mg and Ca)

2 electrons in outer shell

Transition Metals

Elements in groups 3-12

Less reactive harder metals

Includes metals used in jewelry and construction.

Metals used “as metal.” Higher densities and

melting points than groups 1 and 2.

Lanthanides and Actinides

Transition metals placed here to keep periodic table from being too wide.

Named for the elements that they follow. Lanthanides:

Shiny, reactive metals, used in steel manufacturing Actinides:

Radioactive (unstable) Synthetic past U!

Boron Family/Group

Elements in group 13 Aluminum metal was

once rare and expensive, not a “disposable metal.”

Contains 1 metalloid and 4 metals

3 electrons in outer level

Solid at room temperature

Carbon Family/Group Elements in group 14 Contains elements

important to life and computers.

Carbon is the basis for an entire branch of chemistry.

Silicon and Germanium are important semiconductors.


Nitrogen Family Elements in group 15 Nitrogen makes up

over ¾ of the atmosphere.

Nitrogen and phosphorus are both important in living things.

The red stuff on the tip of matches is phosphorus.


Oxygen Family/Group

Elements in group 16 Oxygen is necessary

for respiration. Many things that stink,

contain sulfur (rotten eggs, garlic, skunks,etc.)

6 outer electrons

Halogens

Elements in group 17 Very reactive, volatile,

diatomic, nonmetals Always found combined

with other element in nature .

Used as disinfectants and to strengthen teeth.

7 outer electrons

The Noble Gases

Elements in group 18 VERY unreactive,

monatomic gases Used in lighted “neon”

signs Used in blimps to fix

the Hindenberg problem.

Have a full valence shell.

Reactivity

Noble Gases are at the far right of the periodic table.

Reactivity increases as you go to the left and the top of the periodic table.

Chemical Bonding

A chemical bond is the force of attraction that holds two atoms together.

The key to bonding is found in the number of valance electrons.

Valance electrons: electrons that are in the outermost energy level of an atom

Remember the goal is to have 8 valance electrons (exception H and He)

Chemical Bonding The oxidation number of an atom is the

charge that atom would have if the compound was composed of ions.

Bonding: Ionic, Covalent, Metallic

Ionic bond: forms between a metal and a nonmetal where the metal gives up an electron to the nonmetal and the resulting oppositely charged ions attract each other.

Bonding: Ionic, Covalent, Metallic Covalent bond: involves the sharing of

electrons between atoms Can exist as a single, double, or triple bond

(C, O, N)

Bonding: Ionic, Covalent, Metallic

Metallic bond: gives metals their unique characteristics due to delocalized electrons that can flow throughout the metal

Occurs in transition metals.

Predicting bonding First determine how

many e- are in the atoms outer shell.

Next determine whether it is likely to lose or gain e- or if it is able to share e-.

Ionic=nonmetal+metal Covalent =

nonmetal + nonmetal

Predict whether the following will form ionic, covalent, or metallic bonds.

Carbon and Carbon Cadmium and Cadmium Phosphorous and Fluorine Strontium and Selenium

Chemical Reactions A chemical reaction is the process by which

one or more substances undergo change to produce one or more different substances.

Clues a reaction has occurred: Gas formation (bubbles) Precipitate forms (solid) Color change Energy change (heat absorbed or given off)

Chemical formula

A chemical formula is a shorthand way of writing a compound.

It represents the element by the chemical symbol.

It represents the quantity of the element by the subscript.

Writing Covalent Chemical Formulas

Prefixes to know: Mono- 1 Di- 2 Tri- 3 Tetra- 4 Penta- 5

Hexa- 6 Hepta- 7 Octa- 8 Nona- 9 Deca- 10

Use prefixes to tell you the number of atoms of that element!

Writing Covalent Chemical Formulas

Carbon dioxide CO2

Dinitrogen monoxide N2O Dihydrogen monoxide Triphosphorous pentoxide

Writing Ionic Chemical Formulas

Occurs between metals and nonmetals. The compound must be neutral.

Sodium chloride Beryllium oxide Magnesium chloride Calcium chloride

Chemical Equations

Reactants → Products

C + O2 → CO2

***All equations must be balanced!!!*** The law of conservation of mass: mass can

neither be created nor destroyed! The law of conservation of energy: energy can

neither be created nor destroyed!

Practice balancing equations Count the atoms!

Place coefficients to balance the atoms.

Check and finish balancing.

H2 + O2 → H2O H=2 H=2 O=2 O=1

H2 + O2 → 2H2O H=2 H=4 O=2 O=2

2H2 + O2 → 2H2O H=4 H=4 O=2 O=2

Types of Reactions

Synthesis A + X → AX Na + Cl2 → NaCl

Decomposition AX → A + X H2CO3 → H2O + CO2

Types of Reactions

Single-replacement reaction A + BX → AX + B Zn + HCl → ZnCl2 + H2

Double-replacement reaction AX + BY → AY + BX NaCl + AgF → NaF + AgCl

Types of Reactions

Rusting (Slow oxidation) 4Fe + 3O2 → 2Fe2O3

Combustion (Fast oxidation) CH4 + 2O2 → CO2 + 2H20 + Heat

Energy and reactions Exothermic: energy is released (energy may be in

form of light, electrical, or thermal) 2Na + Cl2 → 2NaCl + energy

Endothermic: energy is absorbed or goes into the reaction (ex. Photosythesis) 2H2O + energy → 2H2 + O2

How a reaction gets started

Activation energy: minimum amount of energy needed for substances to react.

Factors that affect reaction rates

Temperature: an increase in temperature increases the rate of the reaction

Concentration: an increase in the amount of reactants increases the rate of the reaction

Surface area: Grinding reactants into powder can increase the rate of reaction


Catalysts: a substance that speeds up a reaction without permanently being changed. Enzymes: proteins in human’s that act as catalyst.


Inhibitors: a substance that slows down or stops a chemical reaction Preservatives act as inhibitors to prevent spoilage

Star Formation

Sun made mostly of Hydrogen. The H exist in an extremely high energy state called plasma.

In stars the pressure is so high that the nuclei of atoms, which normally repel, are joined together. (Nuclear Fusion)

Two Hydrogen atoms collide and produce helium.

Two Helium atoms collide and produce one helium and two Hydrogen atoms.

chemistry. mav marks 1/4/12 sci.html sci.html element challenge

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