Chemistry 121Chemistry 121

Chapter 1:Chapter 1:

Matter and MeasurementMatter and Measurement

Dr. Michael PageDr. Michael Page

Why Are We Studying Chemistry

The universe can is The universe can is

composed of composed of MATTER and ENERGYMATTER and ENERGY CHEMISTRYCHEMISTRY: is the study that : is the study that

examines the composition, properties, examines the composition, properties, and transformation of matterand transformation of matter

Matter MatterMatter is the basis of the human body, is the basis of the human body,

medicine, pharmaceuticals, polymers, metals, medicine, pharmaceuticals, polymers, metals, and plastics.and plastics.

Matter is composed of basic Matter is composed of basic elementselements..

Chemistry is an Experimental Science

Everything in your text Everything in your text BOOK BOOK was discovered in a was discovered in a LABLAB

Chemistry is composed of a Chemistry is composed of a body of scientificbody of scientific Theories Theories that are based on that are based on experimental observationsexperimental observations

Periodic Table

ElementsElements are the fundamental are the fundamental substance that cansubstance that can’’t be chemically t be chemically changed or broken down into anything changed or broken down into anything simpler.This is the most important simpler.This is the most important organizing principle in chemistry.organizing principle in chemistry.

The first modern periodic The first modern periodic table was published in 1869 table was published in 1869 by Dmitri Medeleev.by Dmitri Medeleev.

Periodic Table

7 periods (electronic configuration)

18 groups (reactivity)

Main Group (elements of life)

Transition Metals

Main Group Elements (Named)

Group 1A-Alkali metalsGroup 1A-Alkali metalsLithium (Li) Sodium (Na)Lithium (Li) Sodium (Na)Potassium (K) Potassium (K) Rubidium (Rb) Cesium (Cs)Rubidium (Rb) Cesium (Cs)

Soft Silvery metals that Soft Silvery metals that react with water.react with water.

Main Group Elements (Named)

Group 2A-Alkaline earth Group 2A-Alkaline earth metalsmetalsBeryllium (Be), Magnesium Beryllium (Be), Magnesium (Mg), Calcium (Ca), (Mg), Calcium (Ca), Strontium (Sr), Barium (Ba),Strontium (Sr), Barium (Ba),Randium (Ra).Randium (Ra).

Soft Silvery metalsSoft Silvery metals

Main Group Elements (Named)

Group 7A-HalogensGroup 7A-HalogensFluorine (F), Chlorine (Cl)Fluorine (F), Chlorine (Cl)Bromine (Br), and Iodine (I) Bromine (Br), and Iodine (I)

Halogens that are colorful Halogens that are colorful nonmetals that usually formnonmetals that usually formsalts.salts.

Main Group Elements (Named)

Group 8A-Noble GasesGroup 8A-Noble GasesHelium (He), Neon (Ne),Helium (He), Neon (Ne),Argon (Ar), Xenon (Xe),Argon (Ar), Xenon (Xe),and Radon (Rn)and Radon (Rn)

Colorless gas that have veryColorless gas that have verylow chemical reactivity.low chemical reactivity.

Other Main Group Elements

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

Metals

All except Mercury (Hg) are All except Mercury (Hg) are solid at room temperature.solid at room temperature.Most of them have a metallicMost of them have a metallicsilvery shine.silvery shine.Metals: 1) MalleableMetals: 1) Malleable (can be (can be twisted and pulled into wirestwisted and pulled into wireswithout breaking).without breaking).2) 2) Good conductorsGood conductors of of electricity.electricity.

Metals (Groups 1B-8B)

Transition MetalsTransition Metals (Elements in groups 1B-(Elements in groups 1B-8B).8B).

2) 2) Inner Transition MetalsInner Transition Metals (Lanthanide and Actinide (Lanthanide and Actinide series)series)

Nonmetals

The nonmetals are mostly The nonmetals are mostly bright colorsbright colors. The ones that . The ones that are solid at room temperature are solid at room temperature are are brittlebrittle (can easily break). (can easily break).

Nonmetals are Nonmetals are poor poor conductorsconductors..

Semimetals (Metaloids)

Metaloids separate the metals Metaloids separate the metals and nonmetals. Their and nonmetals. Their characteristics are characteristics are intermediate in nature. intermediate in nature.

Silvery in colorSilvery in colorSolid at room temperatureSolid at room temperatureBrittleBrittlePoor ConductorsPoor Conductors““SemiconductorsSemiconductors”” Silicon (Si) Silicon (Si)

Whenever you measure something (volume, Whenever you measure something (volume, weight, length, temperature) there is always some weight, length, temperature) there is always some degree of uncertainty.degree of uncertainty.

Generally the last digit in a reported measurement Generally the last digit in a reported measurement is uncertain (estimated).is uncertain (estimated).

0 1 2 43cm

1.7cm < length > 1.8cm1.7cm < length > 1.8cm 1.74cm1.74cm

4.803 cm 4 SF

Rules for counting significant figures (left-to-right):

1. Zeros in the middle of a number are like any other digit; they are always significant.

0.00661 g 3 SF (or 6.61 x 10-3 g Scientific Notation)

Rules for counting significant figures (left-to-right):

1. Zeros in the middle of a number are like any other digit; they are always significant.

2. Zeros at the beginning of a number are not significant (placeholders).

55.220 K 5 SF (or 5.5220 x 101 K)

Rules for counting significant figures (left-to-right):

1. Zeros in the middle of a number are like any other digit; they are always significant.

2. Zeros at the beginning of a number are not significant (placeholders).

3. Zeros at the end of a number and after the decimal point are always significant.

Rules for counting significant figures (left-to-right):

1. Zeros in the middle of a number are like any other digit; they are always significant.

2. Zeros at the beginning of a number are not significant (placeholders).

3. Zeros at the end of a number and after the decimal point are always significant.

4. 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)

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.

11.70 gal

278 mi= 23.8 mi/gal

4 SF

3 SF

3 SF

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.

3.19

+ 0.013153.18

2 decimal places

5 decimal places

2 decimal places

• 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

Rounding Rules