Texas TEKS 7.6

7.6 is a TEKS knowledge and skills statement. These are the student expectations under it.

• 7.6.A

  compare and contrast elements and compounds in terms of atoms and molecules, chemical symbols, and chemical formulas

• 7.6.B

  use the periodic table to identify the atoms and the number of each kind within a chemical formula

• 7.6.C

  distinguish between physical and chemical changes in matter

• 7.6.D

  describe aqueous solutions in terms of solute and solvent, concentration, and dilution

• 7.6.E

  investigate and model how temperature, surface area, and agitation affect the rate of dissolution of solid solutes in aqueous solutions.

01

What Students Need to Do

Students tell elements from compounds by reading particle models, symbols, and formulas. They use the periodic table and subscripts to identify the atoms in a formula and count each kind. They classify changes, describe concentration and dilution, and test factors that change dissolution rate.

02

What Mastery Looks Like

Given CaCl2, a student identifies the elements and counts one calcium atom and two chlorine atoms. The student classifies observed changes and cites evidence such as gas formation or a new color. The student labels solute and solvent, compares concentrations, and predicts dissolution rates when temperature, particle size, or stirring changes.

03

Common Misconceptions

Students often treat subscripts as coefficients, count element symbols incorrectly, or assume every molecule is a compound. They may call dissolving a chemical change because the solid disappears, or confuse melting with dissolving. They also confuse faster dissolution with greater solubility and think stirring increases the final amount that can dissolve.

04

How to Assess It

Give students an exit ticket showing Na2CO3, melting wax, rusting iron, two saltwater mixtures, and sugar stirred in hot or cold water. Ask them to count atoms, classify changes, label solution parts, compare concentration, and predict faster dissolution.

1. 01

   At three stations, time equal sugar samples dissolving while changing only water temperature, crystal size, or stirring.

2. 02

   Ask students why O2 is an element but H2O is a compound, using atoms, molecules, symbols, and formulas.

3. 03

   Run a card sort with element samples, compound samples, physical changes, and chemical changes, then require evidence for each placement.

4. 04

   Mix two sports drink concentrations, calculate each recipe's solute-to-water ratio, and connect dilution to label directions.

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