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Chemistry 121

Chemistry 121. Chapter 1: Matter and Measurement Dr. Michael Page. Why Are We Studying Chemistry. The universe can is composed of MATTER and ENERGY CHEMISTRY : is the study that examines the composition, properties, and transformation of matter. Matter.

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Chemistry 121

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  1. Chemistry 121 Chapter 1: Matter and Measurement Dr. Michael Page

  2. Why Are We Studying Chemistry • The universe can is composed of MATTER and ENERGY • CHEMISTRY: is the study that examines the composition, properties, and transformation of matter

  3. Matter • Matter is the basis of the human body, medicine, pharmaceuticals, polymers, metals, and plastics. • Matter is composed of basic elements.

  4. Chemistry is an Experimental Science • Everything in your text BOOK was discovered in a LAB • Chemistry is composed of a body of scientific Theories that are based on experimental observations

  5. Periodic Table • Elements are the fundamental substance that can’t be chemically changed or broken down into anything simpler.This is the most important organizing principle in chemistry. • The first modern periodic table was published in 1869 by Dmitri Medeleev.

  6. Periodic Table • 7 periods (electronic configuration) • 18 groups (reactivity) • Main Group (elements of life) • Transition Metals

  7. Main Group Elements (Named) Group 1A-Alkali metals Lithium (Li) Sodium (Na) Potassium (K) Rubidium (Rb) Cesium (Cs) Soft Silvery metals that react with water.

  8. Main Group Elements (Named) Group 2A-Alkaline earth metals Beryllium (Be), Magnesium (Mg), Calcium (Ca), Strontium (Sr), Barium (Ba), Randium (Ra). Soft Silvery metals

  9. Main Group Elements (Named) Group 7A-Halogens Fluorine (F), Chlorine (Cl) Bromine (Br), and Iodine (I) Halogens that are colorful nonmetals that usually form salts.

  10. Main Group Elements (Named) Group 8A-Noble Gases Helium (He), Neon (Ne), Argon (Ar), Xenon (Xe), and Radon (Rn) Colorless gas that have very low chemical reactivity.

  11. Other Main Group Elements Also Include Groups 3A-6A All the elements in these groups are also considered Main Group Elements!

  12. Metals All except Mercury (Hg) are solid at room temperature. Most of them have a metallic silvery shine. Metals: 1) Malleable (can be twisted and pulled into wires without breaking). 2) Good conductors of electricity.

  13. Metals (Groups 1B-8B) Transition Metals (Elements in groups 1B-8B). 2) Inner Transition Metals (Lanthanide and Actinide series)

  14. Nonmetals The nonmetals are mostly bright colors. The ones that are solid at room temperature are brittle (can easily break). Nonmetals are poor conductors.

  15. Semimetals (Metaloids) Metaloids separate the metals and nonmetals. Their characteristics are intermediate in nature. Silvery in color Solid at room temperature Brittle Poor Conductors “Semiconductors” Silicon (Si)

  16. 0 1 2 3 4 1.7cm < length > 1.8cm 1.74cm cm Whenever you measure something (volume, weight, length, temperature) there is always some degree of uncertainty. Generally the last digit in a reported measurement is uncertain (estimated).

  17. Rules for counting significant figures (left-to-right): Zeros in the middle of a number are like any other digit; they are always significant. 4.803 cm 4 SF

  18. Rules for counting significant figures (left-to-right): Zeros in the middle of a number are like any other digit; they are always significant. Zeros at the beginning of a number are not significant (placeholders). 0.00661 g 3 SF (or 6.61 x 10-3 g Scientific Notation)

  19. Rules for counting significant figures (left-to-right): Zeros in the middle of a number are like any other digit; they are always significant. Zeros at the beginning of a number are not significant (placeholders). Zeros at the end of a number and after the decimal point are always significant. 55.220 K 5 SF (or 5.5220 x 101 K)

  20. Rules for counting significant figures (left-to-right): Zeros in the middle of a number are like any other digit; they are always significant. Zeros at the beginning of a number are not significant (placeholders). Zeros at the end of a number and after the decimal point are always significant. Zeros at the end of a number without a decimal point may or may not be significant. 34,200 m 3 or 5 SF (or 3.42 x 104 m)

  21. 278 mi 11.70 gal Math rules for keeping track of significant figures: • Multiplication or division: The answer can’t have more significant figures than any of the original numbers. 3 SF = 23.8 mi/gal 4 SF 3 SF

  22. Math rules for keeping track of significant figures: • Multiplication or division: The answer can’t have more significant figures than any of the original numbers. • Addition or subtraction: The answer can’t have more digits to the right of the decimal point than any of the original numbers. 2 decimal places 5 decimal places 2 decimal places 3.18 + 0.01315 3.19

  23. Rounding Rules • If the first digit to be dropped is less than 5, round down. • If the first digit to be dropped is greater than 5, round up. • If the first digit to be dropped is 5 and there are nonzero numbers following the 5, round up. • If the first digit to be dropped is 5 with nothing following, round down. • Round these numbers to 1 decimal place 14.468 6.521 20.552 18.65

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