Chemistry 2

Bell Work 12/2/09 Find the number of valance electrons for each of the following elements and name the ion that would make it “happy and full” Sodium - Na Oxygen - O Chlorine - Cl Boron - B Aluminum - Al

Radioactive Decay Radioactive atoms produce energy and particles from their nuclei. The identity of these atoms changes because the number of protons changes. Occurs at a steady rate that is characteristic of the particular isotope Half-life – the amount of time it takes for one-half of the atoms in a particular sample to decay

Ions – a charged atom, positive or negative charge. The fewer electrons per shell the less energy needed to pull the electrons away from that element. The greater the amount of electrons per shell the higher the energy needed to “pull” the electrons away from that element.

Ionic bonding – bonding that involves a transfer of electrons. Elements tend to want a full outer shell, thus giving up electrons to other elements or gathering electrons from other elements. Occurs between a metal and nonmetal Example Na + and Cl - Mg 2+ and O 2-

Bell Work 12/3/09 Draw a picture of each of the following and show which element gives away their electrons to the other. Then name the Ionic Bond 1.Li and F 2.Mg and S 3.K and Br 4.Ca and O

Naming an Ionic Bond (Example NaCl) 1.List the name of the metal (Na – Sodium) 2.Change the ending of the nonmetal to –ide (Cl – Chlorine changes to Chloride) 3.Put the two names together listing the metal first then the renamed nonmetal (Sodium Chloride)

Bell Work 12/4/09 Draw a picture of each of the following and show which element gives away their electrons to the other. Then name the Ionic Bond 1.Na and Cl 2.K and S 3.Li and N 4.Cs and I

Covalent bonds Covalent bonding – Bonding of atoms in which electrons are shared. Occurs between two nonmetals exp. H H

Metallic Bonding Metallic bond – bond formed by atoms of metals, in which the outer electrons of the atoms form a common electron cloud. The atoms of metals form metallic bonds

metals are elements that give up electrons easily. The atoms of metals form metallic bonds because the electrons have loose bonds that have the ability to move freely in the cloud without breaking the bond

Bell Work 12/7/09 1.What is an ionic bond? 2.What is a covalent bond? 3.What is a metallic bond? State what type of bond each of the following are 4. CO 2 5. NaCl 6. N 2 7. BiK 3

THE BIG DEAL Chemical reactions occur when chemical bonds break or when new bonds form. This is the Conservation of mass by transferring energy from one atom to another creating a new substance made of two atoms instead of two atoms being two separate substances.

Physical properties of metals Ductile – The ability to be stretched without breaking. Malleable – the ability to be flattened or hammered and still hold together. Conductor – something that has the ability to carry heat or electricity.

Physical Change – A change that alters the form or appearance of a material but does not make the material into another substance. Evidence of a physical change 1. cutting hair 2. color of skin 3. phase change (solid to liquid) 4. size 5. shape 6. viscosity (thick or thin of liquid)

PHASE CHANGE Solid liquid and gas are states of matter that depend on the temperature of the matter. Exp. Water is a solid at 31 degrees Fahrenheit. But if you increase the energy of the atoms of water the water will change state to a liquid. By adding energy you can change the state of all matter. Energy is in the electrons!!!!!!

Chemical Change – A change in matter that produces a new substance. Evidence of a chemical change CHANGE in color Production of a gas / ODOR / bubbling Precipitate formation (solid in liquid) production of heat loss of heat (gets colder) emission of light

The key characteristic of a chemical reaction is the production of new materials that are chemically different from the starting materials. Precipitate – A solid that forms from a solution during a chemical reaction.

Compound – A substance made of two or more elements chemically combined in a specific ratio, or proportion. Mixture – Two or more substances that are mixed together but not chemically combined. Solution – A well mixed mixture.