Unit 1 Sec. A Summary HW 2

6/17/14

6) a. Step 1: Whisk together in a bowl flour and baking soda. Combine butter, sugar, salt, vanilla, and eggs. Mix together and add chocolate chips

Step 2: Drop a tablespoon of dough on a backing sheet.

Step 3: Bake the cookies in the oven for 8-10 minutes

b. Step 1: physical change

Step 2: physical change

Step 3: chemical change

7) Substance is an element or a compound that has a uniform and definite composition. Examples are water and sugar.

8) a. CO compound

b. Co element

c. HCl compound

d. Mg element

e. NaHCO₃ compound

f. NO compound

g. I₂ element

9) a. i, ii, iv, vi represent elements

b. iii, v represent compounds

10) The chemical formula provides the elements and the subscript, which is the number of atoms of the element.  

11) The chemical symbol is the “letter” which is the abbreviation of an elements name and the chemical formulas is the “word” which represents the different chemical compounds.

Concept Check pg. 35

1) Pure copper (8.94 g/cm³) is denser than pure zinc (7.14 g/cm³).

2) In a 1982 penny, the coin’s body was composed of zinc and the coin’s surface was composed of a thin copper outer layer.

3) Based on figure 1.9 I was able to come with a conclusion that the penny is composed more of zinc than copper and the penny is coated in a thin outer layer of copper.

A.7 Questions pg. 38

1) a. P phosphorus

b. Ni nickel

c. Cu copper

d. Co cobalt

e. Br bromine

f. K potassium

g. Na sodium

h. Fe iron

2) Phosphorus, nickel, cobalt, and bromine all have symbols corresponding to their English names.

3) An element’s symbol is more likely to be the same throughout to world because of the periodic table. 

4) a. H₂O₂ – elements: hydrogen and oxygen

                     number of atoms: 2 hydrogen and 2 oxygen

b. CaCl₂ – elements: calcium and chlorine

                number of atoms: 1 calcium and 2 chlorine

c. NaHCO₃ – elements: sodium, hydrogen, carbon, and oxygen

                number of atoms: 1 sodium, 1 hydrogen, 1 carbon, and 3 oxygen

d. H₂SO₄ – elements: hydrogen, sulfur, and oxygen

                number of atoms: 2 hydrogen, 1 sulfur, 4 oxygen

5) Two molecules of hydrogen react with one molecule of oxygen to form to molecules of water.

   Chemical equation: 2H₂ + O₂ ––> 2H₂O