6.5ABC Elements and Compounds Question Answers p. 1-6

Directions: Using a red pen or other colored pen, go through this power point and correct the questions in your journal workbook. Make sure you have the correct answers so that when it comes time to study for the unit test you will be prepared!

Page 2-Matter Question 6- A pure substance is matter that is made of only one kind of matter, it is uniform throughout and has consistent properties. Both elements and compounds are considered pure substances Question 7- An element is a pure substance that is made of only one type of atom that cannot be broken down into a simpler substance. Ex. H, He, C, O 2 Question 8- Elements are identified by the element’s name, symbol, atomic number and atomic mass

Page 2 (continued) Question 9-One or two letter symbols identify an element. If it is a single lettered element, the symbol is always capitalized. Ex. H, B, C, O, N. If it is a two lettered symbol the first letter is capitalized, the second is lower case. Ex. He, Na, Ca, Xe, Au Question 10- The elements found in all four components of the Earth (biosphere, atmosphere, lithosphere, hydrosphere) are Hydrogen and Oxygen

Page 3 Question 1-Both elements and compounds are made of elements and are pure substances. Both have a definite set of properties. Both can be represented by chemical symbols Question 2- Elements are made of only one type of atoms (ex O, O 2, H, C 3, Na, Ag) Elements are listed on the periodic table, compounds are not. Compounds are represented by more than one chemical symbol. Compounds may be broken down into simpler substance, elements can not.

Page 5 Question 1-The periodic table is useful in that if you have the symbol you can use that to locate the element’s name, or you can find the name if you have the only the symbol. Question 2- Both compounds and mixtures have more than one material in them, but compounds are pure substances with defined ratios of elements (ex. H20 has a ration of 2:1. Two hydrogen atoms bonded to 1 oxygen atom) and are not easily broken apart. Mixtures can more easily be separated by physical means such as filtering, sorting, evaporating or using magnetic attraction if there is metal in the mixture. Compounds have definite properties different from the properties of the individual elements that make up them. Ex. Salt, NaCl is a relatively harmless substance we eat but Na by itself is explosive and Cl is poisonous if consumed in large quantities.

Page 6 Question 1- H= Element CO 2 =Compound Co=Element Ca=Element CaCO 2 =Compound O=Element N=Element SiO 2 =Compound

Page 6 Question 2-A compound is two or more elements that form a pure substance which can only be broken down into simpler substances by a chemical reaction. Question 2-The elements that are present in a compound are in a fixed ration and uniform throughout, therefore it is considered a pure substance. Question 4- Only a small percent of the known elements are found in significant amounts in the various components(biosphere, lithosphere, atmosphere, hydrosphere) of the Earth.

Page 6 continued Question 5-The advantage of using the snap together toy to model compounds may be that each of the individual “bricks” cannot be broken down into smaller pieces, Bricks of the same color can represent atoms of an element, the bricks can be put together to represent compounds. Question 6- A disadvantage of using the snap together toy to model compounds may be that they don’t actually show the real item, the size or shape of the compound.