Objective 4

It’s your turn. Read the information on the slides to help remind you about what you know about atoms and the Periodic Table. You will need to click through the program at your own pace. Everyone should have a pencil or highlighter to mark important ideas.

Objective 4: I 7E The student knows relationships exist between properties of matter and its components. The student is expected to classify samples of matter from everyday life as being elements, compounds, or mixtures

Atomic Theory Atoms are building blocks of elements Atoms of the same element are similar Atoms of different elements are different Two or more different atoms bond in simple ratios to form compounds

Subatomic Particles There are three subatomic particles: Electrons, e - Charge = 1- Protons, p + Charge = 1+ Neutrons, n o No charge, 0 The number of protons identifies an element.

Location of Subatomic Particles electrons (outside (inside nucleus) nucleus) protons neutrons nucleus

Atomic Number Counts the number of protons in an atom

Atomic Number on the Periodic Table 12 Mg Atomic Number Symbol (12 p+)

All atoms of an element have the same number of protons 11 Na 11 protons Sodium All sodium atoms have 11 protons.

Mass Number Counts the number of protons and neutrons in an atom

Atomic Symbols Show the mass number and atomic number Give the symbol of the element mass number 23 Na sodium atomic number

Subatomic Particles in Some Atoms O P Zn p + 8 n 0 8 e - 15 p+30 p+ 16 n 0 15 e- 30 e- 35 n 0

Atomic Mass on the Periodic Table 6 C Atomic Number Symbol Atomic Mass

Sodium-23 mass number

Students, Answer released TAKS question #1 on your sheet. Now, turn to your Periodic Table and follow along!

Properties of Metals: luster, ductile, malleable, good conductors of heat and electricity, lose electrons to form + ions Metals

Label the Metals on your Periodic Table.

Properties of Nonmetals: dull, brittle, insulators (poor conductors), gain electrons to form – ions Nonmetals

Label the Nonmetals on your Periodic Table.

Metalloid (Semimetals) are elements that border the diagonal line between metals and nonmetals. Metalloids have some properties of both metals and nonmetals. They act as a metal with a nonmetal or as a nonmetal with a metal. Metalloids or semimetals

Label the Metalloids on your Periodic Table.

NOBLE GASES Group (VIIIA) 18: Noble gases are stable and do not bond!

Students, flip back to “More Objective 4”

Period A horizontal row in the periodic table. Label!

Group The elements in a vertical column of the periodic table. Label!

group Elements in the same group have similar properties

Periodic Law repeatPhysical and chemical properties of the elements repeat in a regular pattern when they are arranged in order of increasing atomic number. Find Oxygen

Did you find Oxygen ? What elements do you think have properties similar to Oxygen? Elements in the same group: S, Se, Te, Po O

Students, answer the released TAKS questions on your sheet.

Answer Key 1. B 2. D 3. C 4. D 5. G 6. C 11. C 7. B 12. D 8. A 9. D 10. B

Objective 4 Part 2

Read the information on the slides to help remind the students what they know about the law of conservation of mass. You will need to click through the program at your own pace. Everyone should have something to write with.

Objective 4: IPC 8C The student will investigate and identify the law of conservation of mass.

Chemical Equations: An expression in which symbols and formulas are used to represent a chemical reaction. sodium metal + chlorine gas  table salt ( sodium chloride)

A chemical equation identifies the starting and ending chemicals as reactants and products: reactants  products Formation of water 2H 2 + O 2  2H 2 0 A chemical equation is balanced when it reflects the law of conservation of mass. Graphic: state.edu/betha/nealChemBal/

The Law of conservation of mass states that matter cannot be created or destroyed in any chemical reaction The atoms in the reactants are rearranged to form new compounds, but none of the atoms disappear, and no new atoms are formed. H H H H O O Reactants Products

Remember that atoms don’t change in a chemical reaction. The number and kinds of atoms present in the reactants of a chemical reaction are the same as those present in the products. When stated this way, it becomes the law of conservation of atoms.

So: Chemical equations are balanced, when the numbers and kinds of atoms on each side of the reaction arrow are equal. H H H H O O Reactants Products H H H H O O 4 Hydrogen 2 Oxygen

Coefficients, the numbers placed in front of formulas to balance equations. They indicate the number of particles present in the reaction. If a number is not present it is understood that 1 is the coefficient. 2 H 2 + O 2  2 H 2 O

2H 2 O Coefficient subscript Coefficients are used to balance equations. NEVER change or add subscripts!

When balancing a chemical equation, first you must determine the number of each kind of atom on each side of the yield arrow. Ca + O 2  CaO 1 Ca atom 2 O atoms 1 Ca atom 1 O atom Notice that there are the same number of calcium atoms on each side of the equation but the number of oxygen atoms are not the same. This equation is not balanced.

Ca + O 2  CaO Coefficients are needed to make the number of oxygen atoms equal. A coefficient 2 is placed in front of CaO. 1 Ca atom 2 O atoms 1 Ca atom 1 O atom 2 This coefficient indicates 2 Ca atoms and 2 oxygen atoms. Now calcium is not equal. A coefficient of 2 in placed in front of Ca The number of each kind of atom are equal on both sides of the yield arrow. This equation is now balanced and follows the law of conservation of mass Ca atom 2 1 O atom 2 1 Ca atom 2 O atoms

2 Notice that the number of hydrogen and oxygen atoms are equal 2 The number of oxygen atoms are not the same so the equation is balanced with coefficients.

Balancing Chemical Equations The following five steps can be used as a guide to balance chemical equations. Balance this chemical reaction. Sulfuric Acid reacts with sodium hydroxide to yield sodium sulfate and water Step 1: Write an unbalanced equation, using correct formulas for all reactants and products. H 2 SO 4 + NaOH  Na 2 SO 4 + H 2 O

Step 2: Inventory all atoms found in the equation H 2 SO 4 + NaOH  Na 2 SO 4 + H 2 O 2 H + 1 H = 3H 2 Na 1 S 4 O + 1 O = 5 O 4 O + 1 O= 5 O 1 Na 2 H

Step 3: Compare the number of each atom on each side of the equation. Add coefficients to balance the number of atoms. Remember that adding a coefficient affects all elements in the compound. H 2 SO 4 + NaOH  Na 2 SO 4 + H 2 O 2 H + 1 H = 3H 2 Na 1 S 1 S 4 O + 1 O = 5 O 4 O + 1 O= 5 O 1 Na 2 H 22 4H 6O 4H 6 O 2 Na Equal

Step 4: Check the equation to make sure the numbers and kinds of atoms on both sides of the equation are same. H 2 SO NaOH  Na 2 SO H 2 O 2 H + 2 H = 4H 2 Na 1 S 1 S 4 O + 2 O = 6 O 4 O + 2 O= 6 O 2 Na 4 H

Step 5: Make sure the coefficients are reduced to their lowest whole- number value (ok here). H 2 SO NaOH  Na 2 SO H 2 O 1 : 2: 1 : 2

Balance the next equation on your own. Talk to your neighbors and decide what the coefficients are that balance the equation.

Students, answer the released TAKS questions on your sheet.

1. D 2. D 3. C 4. B 5. C 6. B 7. B 8. D