Goal 4 EOG REVIEW The learner will conduct

Goal 4 EOG REVIEW The learner will conduct investigations and utilize technology and information systems to build an understanding of chemistry.

Identifying Chemicals • Chemical: a substance used in or formed by a chemical process. It is also any substance with definite composition (meaning it is always made up of the same substances). For example, water will always be made up of one part oxygen and two parts of hydrogen. • We have two categories for chemicals: natural and synthetic.

Con’t • Natural chemicals: exist in nature ex. Water, air • Synthetic chemicals: not naturally occurring, and is made in laboratories by people. Ex. Steel and bronze, medicines • Matter: anything that has mass and volume. • Mass: the amount of matter in a substance. • Volume: the amount of space the substance occupies.

Con’t • Three states of matter: – Solid: has definite shape and volume – Liquid: has a definite volume but not shape – Gas: has neither a definite shape or volume • Elements: a substance that cannot be broken down into simpler substances. Ex. Hydrogen, oxygen, carbon • We have 109 known elements on the periodic chart that have been discovered by man.

Con’t • Of the 109 known elements, 92 are naturally occurring. • Elements can combine in different ways to form mixtures or compounds. – Mixture: a type of matter that forms when two or more substances are combined but do not chemically join. Ex. Cereal, air – Compound: a type of matter that forms when two or more elements combine CHEMICALLY. This will form a new substance different than the original reactants. Ex. Na combining with Cl will give you table salt. Na starts out as a metal and Cl is a poisonous gas, but when you combine them you get table salt.

Elements Form Compounds • Compounds have 3 important characteristics: – A definite composition – Can be broken down into simpler substances by chemical means – Can be identified by their physical properties • Molecule: the smallest unit of a compound that has all the properties of the compound. We represent the make-up of a molecule in a chemical formula. – Chemical formula: chemical symbols and subscripts that identify the number of atoms of each element in a molecule of a compound.

Con’t – Ex. Chemical formula for water is H O. 2 • Atoms: the smallest unit of an element that has all the properties of the element. They are the building blocks of matter. • Atoms are made up of three types of particles: – Protons: have a positive charge and reside in the nucleus – Neutrons: have a neutral (or no) charge and also reside in the nucleus – Electrons: have a negative charge and reside in the electron cloud (energy levels)

Con’t • For more on atoms go to http: //education. jlab. org/atomtour/ • http: //www. school-forchampions. com/science/atom. html • Each energy level of an atom can hold only a specific number of electrons.

Con’t Energy Level 1 Maximum Number of Electrons 2 2 8 3 18 4 32

Con’t • Valence electrons: the electrons in the outermost energy level of an atom. These are the electrons that participate in bonding. • Chemical bonding: the exchange of electrons that hold atoms together. There are two types: ionic and covalent – Ionic: When two atoms bond and one atoms loses a(n) electron(s) and the other gains. For example, when Na bonds with Cl, the Na will lose one electron and the Cl will gain one electron.

Con’t – Because they are bonded, both Na and Cl will now have a full outside energy level. – All atoms participate in bonding for one reason only…. to get a full outside energy level. – Atoms that are in groups 1, 2, and 3 will lose their valence electrons. Atoms in groups 5, 6, and 7 will gain valence electrons. – Ionic bonds are formed by combining atoms that are metal with ones that are nonmetal.

Con’t – Covalent bonding: formed when two atoms share valence electrons. This is also done to fill the outside energy level with valence electrons. But in this kind, no one loses or gains. Everyone shares. • Happens between two nonmetals. • Ex. 2 Hydrogens will share one electron each with Oxygen to form water. • Elements can combine in a multitude of different ways to form many different substances. For example, H 2 O is water but H 2 O 2 is hydrogen peroxide.

Con’t • Atomic theory: – All matter is composed of atoms – Atoms of a given element are identical – Atoms of different elements combine in simple whole-number rations to form chemical compounds (this is why you can not have a coefficient or subscript with a decimal). • Compounds are found in both living and nonliving things

The Periodic Table • Mendeleev tried to find a way to organize info about the known elements of his time. • He wrote each element’s name and properties on a separate card. • He looked for a pattern in the properties of the elements that could be used to classify and keep info about them in an organized way.

Con’t • Periodic table: a chart that organizes info about all of the known elements according to their properties. It is organized by atomic number. • Atomic number: the number of protons contained in the nucleus of the atom. • Atomic mass: the number of protons plus neutrons in the nucleus of one atom of the element.

Con’t • Period: the horizontal row in the periodic table. There are 7 periods. • Group or Family: the vertical columns on the periodic table. There are 18 groups. Group number determines the number of valence electrons. – For example, if you have an element from Group 1 then the atom will have 1 valence electron. The number of the group number = the number of valence electrons.

Con’t – But, for familys 11 -18, you have to drop the first digit of the family number. So, if you have an element from group 17, then it will have 7 valence electrons. • Reactivity: how likely an element is to form bonds with other elements. The most chemically active metals are group 1, and they are called Alkali metals. – Group 2 are called alkaline earth metals. They are slightly less reactive than group 1.

Con’t • Groups 3 -12 are called the transition metals. • Metalloids: elements that have some properties of both metals and nonmetals. They fall along the jagged line of the periodic table between the metals and nonmetals. • Group 17: Halogens, the are the most reactive nonmetals. • Group 18: Noble gases, they are the least reactive of all elements because their outside energy level is full. – Inert: unable to react chemically.

Con’t • Properties of Metals and Nonmetals Metals Nonmetals Solid at room temp, except Mercury Malleable and ductile Gases, except Bromine Luster- shiny Dull, not shiny or bright Highly conductive- carry electrical current Tend to lose electrons in chemical reactions Poor conductors Brittle Tend to gain electrons in chemical reactions

Websites • http: //www. chem 4 kids. com/files/elem_intro. html • http: //www. chem 4 kids. com/files/elem_pert http: //www. chem 4 kids. com/files/elem_metal. html able. html • http: //www. chem 4 kids. com/files/elem_fami lies. html • http: //www. chem 4 kids. com/files/elem_met al. html

Properties of Matter • Property: any characteristic that can be used to identify and describe matter. – We have two types: • Chemical: a characteristic that describes how the matter will change under certain conditions. Ex. Ability to burn, rust, react to light, or react with acids. • Physical: any characteristic of a substance that can be observed without changing the identity of the substance. Ex. Mass, volume, color, hardness, and phase.

Con’t • Metals: an element that is a good conductor of electricity and heat, usually solid at room temp, and is on the left-hand side of the periodic table. About 75% of all elements are metals. • Nonmetals: an element that does not readily conduct electricity or heat, usually are gases at room temp. • Metalloids: an element that has some properties of both metals and metalloids.

Con’t • Malleability: able to be hammered and shaped or rolled into thin sheets Ex. Gold can be shaped into necklaces • Ductility: can be stretched or drawn into wires without breaking. Ex. Copper can be made into wire. • Magnetism: a force of attraction or repulsion that exists between like or unlike poles. The metals iron, cobalt, and nickel have strong magnetic properties.

Con’t • Conductor: a material or substance that allows electrons to flow through it easily. • Insulators: materials that do not allow electricity to flow through them easily. • Semiconductor: a material that has conductive properties that are in between conductors and insulators.

Con’t • Density: the ratio of mass to volume – D = mass/Volume – The density of water is 1. 0 g/m. L – When an object is more dense than the liquid it is placed in, it will sink – If is less dense, it will float. • Solubility: a measure of how much of a substance dissolves in a given amount of another substance.

Con’t • Substances can be identified by certain properties. – Physical properties: • Density • Melting point: the temp at which a solid changes to a liquid • Boiling point: the temp at which gas bubbles form in a liquid and rise to the surface and escape the liquid as gas. • Specific heat: the amount of energy needed to raise 1 gram of a substance by 1 degree Celsius. The lower the substance’s specific heat, the faster that substance would rise in temp when heated. • Solubility: a measure of how much of a substance dissolved in a given amount of another substance.

Con’t • Solutions: a mixture in which the particles are too small to be distinguished from each other and remain constantly and uniformly mixed. – Made up of solute and solvent • Solute: the solid that gets dissolved • Solvent: the liquid that dissolves the solute • Example: To make Koolaid, sugar and Koolaid flavoring are the solute that dissolves in water (the solvent).

Con’t • Substances can also be identified by chemical properties like reactivity. – Reactivity: how likely an element is to form bonds with other elements.

Measuring Physical and Chemical Changes • Physical change: alters the physical properties of a substance without altering the identity of the substance. For example, melting ice, tearing a sheet of paper, and sharpening a pencil. • Chemical change: occurs when a substance is changed into a new substance with different properties.

Con’t • A chemical change involves a chemical reaction. – Chemical reaction: the process by which new substances are formed. You can not usually reverse the effects of a chemical change. – Evidence of chemical change: formation of a precipitate (a solid that forms from a chemical reaction that takes place in a solution), gas formation, color change, and energy change.

Con’t • During a chemical reaction, chemical bonds are either broken or formed. Energy is released whenever new bonds from to join substances together. • A chemical reaction is represented by a chemical equation. – Propane + oxygen - carbon dioxide + water + energy – propane and oxygen are the reactants – Carbon dioxide, water, and energy are the products. – The whole thing is the chemical equation

Con’t • Reactant: a substance that takes part in a chemical reaction. • Product: a substance formed during a chemical reaction.

Conservation of matter • The law of conservation of matter: states that during a chemical reaction, matter can not be created or destroyed. So mass does not change nor does the number of atoms. – For example, if you started out with 4 grams of Iron and 3 grams of Oxygen, when they combine you would have to have 7 grams of Iron oxide. – Or if you had 8 Irons and 6 Oxygens before the reaction you would have to have 8 Irons and 6 oxygens after the reaction. So, Fe 8 + O 6 2 Fe 4 O 3

• For practice on balancing chemical equations go to – http: //education. jlab. org/elementbalancing/ind ex. html – http: //www. mpcfaculty. net/mark_bishop/balan cing_equations_tutorial. htm

Harmful Chemicals • Your body comes in contact with many different kinds of chemicals. Some are good for you and some are not. Exposure to harmful chemicals can cause cancer, birth defects, autoimmune diseases, diabetes, heart disease, kidney disease, asthma, and learning or behavioral disorders.

Con’t • Cancer: a group of diseases caused by abnormal cell growth and reproduction. Chemicals that can cause cancer are called carcinogens. Some known carcinogens are cigarette smoke, tar, carbon monoxide, nicotine, arsenic, and cadmium, asbestos, and radon.

Con’t • Chemical exposure can cause birth defects. Birth defects are physical abnormalities that show you in the child at the time of birth of the child. This happens because the mother was exposed to a chemical during the pregnancy. Examples: fetal alcohol syndrome, cleft lip, cleft heart defects.

Con’t • Chemicals can cause heart disease. In this disease, the arteries that supply blood to the heart are narrowed or blocked. Chemicals that can cause heart disease are nicotine and cholesterol. • Chemicals can cause kidney disease. The kidneys are the main organs of the urinary system. They filter out waste products from the blood. When you have kidney disease, your kidneys can no longer filter the waste products out efficiently.

Con’t • Chemicals can cause asthma. A person with asthma has difficulty breathing.

Effects of Chemicals on Organisms • Chemicals are used in industry, agriculture, and in our homes. Some are helpful, and some are harmful to humans and other organisms. • Dose: the amount of a chemical substance that is given to one individual. • Potency: refers to how powerful the chemical is.

Con’t • Exposure time: how long an individual is exposed to a chemical. • Individual susceptibility: how each person is going to respond to a chemical based on the physical and genetic make-up of that individual. • Concentration: the amount of a substance in a given volume.

Con’t • How a person is going to react to a chemical is going to be based on: – Their individual susceptibility – The concentration they receive – The dose – The potency – And how long they were exposed to the chemical.