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Unit 1.5- Sig figs, Chemical Vs. Physical, and E/C/M.

DO NOT CLICK FLASHCARDS FROM HERE (OR STUDY). Click here

Significant figures:

are digits within a number that help determine how accurate a data value or measurement is.

Accuracy Vs. Precision:

  • High Accuracy and High Precision- Multiple correct answers.

  • Low Accuracy and High Precision- Multiple incorrect answers (similar answers).

  • High Accuracy and Low Precision- Varied correct answers.

  • Low Accuracy and Low Precision- Varied incorrect answers.

Rules for sig figs:

  • All numbers that are not zero are significant

  • Zeros in the middle of non-zero numbers are significant

  • Zeros after the decimal are significant

  • Zeros and coefficients in scientific notations are significant

  • Leading or beginning zeros are NOT significant

  • Zeros in a larger number without a decimal are NOT significant

Math rules for sig figs:

  • When adding or subtracting round/look for the least amount of decimal places.

  • When multiplying and dividing look for the least amount of sig figs.

Examples for Sig Figs:

  • Normal examples:

    • 2.2 cm = 2 sig figs

    • 2.22cm = 3 sig figs

    • 100.3cm= 4 sig figs

    • 25.2 mL= 3 sig figs

    • 1002= 4 sig figs

  • Weird examples:

    • 1000 cm= 1 sig fig

    • 1000,= 4 sig figs (, = decimal)

Physical Vs. Chemical:

Physical Change: Does not alter the substance (Changes appearance)

Chemical change: You can never go back to the original substance.

Physical properties (Changes):

  • Freezing and Boiling points (Phases changes)

  • Densities

  • Appearance

  • Ductile (Can be pulled into wire)/ Malleability (Can be flattened into sheets)

  • Brittle

Chemical properties (Changes):

  • Will it burn?

  • What other elements or compounds does it combine with to make compounds?

  • Will it dissolve in water? (Maybe Acid?)

    • Determined by the makeup (Protons/ electrons) of the substance.

Elements/ Compounds/ Mixtures:

Elements:

  • Have certain physical and chemical properties that make them what they are

    • They can be identified by those properties.

      • Density (Physical)

      • number of protons/ Atomic number (Chemical)

Compounds:

  • Two or more elements that have been chemically combined

    • Done through bonding

  • Examples:

    • H20 (water), CO2 (Carbon Dioxide), CO (Carbon monoxide)

  • Can be separated by chemical reactions.

Mixtures:

  • Any of the substances before that have been physically combined.

  • Homogenous- Uniform, same layer (Homo= Same)

  • Heterogenous- Not uniform, seperate layers (Hetero = different)

  • Aqueous mixtures (Aqueous meaning water)

    • aq= dissolved in water

Next Unit: Unit 2- Atoms

CG

Unit 1.5- Sig figs, Chemical Vs. Physical, and E/C/M.

DO NOT CLICK FLASHCARDS FROM HERE (OR STUDY). Click here

Significant figures:

are digits within a number that help determine how accurate a data value or measurement is.

Accuracy Vs. Precision:

  • High Accuracy and High Precision- Multiple correct answers.

  • Low Accuracy and High Precision- Multiple incorrect answers (similar answers).

  • High Accuracy and Low Precision- Varied correct answers.

  • Low Accuracy and Low Precision- Varied incorrect answers.

Rules for sig figs:

  • All numbers that are not zero are significant

  • Zeros in the middle of non-zero numbers are significant

  • Zeros after the decimal are significant

  • Zeros and coefficients in scientific notations are significant

  • Leading or beginning zeros are NOT significant

  • Zeros in a larger number without a decimal are NOT significant

Math rules for sig figs:

  • When adding or subtracting round/look for the least amount of decimal places.

  • When multiplying and dividing look for the least amount of sig figs.

Examples for Sig Figs:

  • Normal examples:

    • 2.2 cm = 2 sig figs

    • 2.22cm = 3 sig figs

    • 100.3cm= 4 sig figs

    • 25.2 mL= 3 sig figs

    • 1002= 4 sig figs

  • Weird examples:

    • 1000 cm= 1 sig fig

    • 1000,= 4 sig figs (, = decimal)

Physical Vs. Chemical:

Physical Change: Does not alter the substance (Changes appearance)

Chemical change: You can never go back to the original substance.

Physical properties (Changes):

  • Freezing and Boiling points (Phases changes)

  • Densities

  • Appearance

  • Ductile (Can be pulled into wire)/ Malleability (Can be flattened into sheets)

  • Brittle

Chemical properties (Changes):

  • Will it burn?

  • What other elements or compounds does it combine with to make compounds?

  • Will it dissolve in water? (Maybe Acid?)

    • Determined by the makeup (Protons/ electrons) of the substance.

Elements/ Compounds/ Mixtures:

Elements:

  • Have certain physical and chemical properties that make them what they are

    • They can be identified by those properties.

      • Density (Physical)

      • number of protons/ Atomic number (Chemical)

Compounds:

  • Two or more elements that have been chemically combined

    • Done through bonding

  • Examples:

    • H20 (water), CO2 (Carbon Dioxide), CO (Carbon monoxide)

  • Can be separated by chemical reactions.

Mixtures:

  • Any of the substances before that have been physically combined.

  • Homogenous- Uniform, same layer (Homo= Same)

  • Heterogenous- Not uniform, seperate layers (Hetero = different)

  • Aqueous mixtures (Aqueous meaning water)

    • aq= dissolved in water

Next Unit: Unit 2- Atoms

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