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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

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

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

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.

Periodic Table

- 7 periods (electronic configuration)
- 18 groups (reactivity)
- Main Group (elements of life)
- Transition Metals

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.

Main Group Elements (Named)

Group 2A-Alkaline earth

metals

Beryllium (Be), Magnesium

(Mg), Calcium (Ca),

Strontium (Sr), Barium (Ba),

Randium (Ra).

Soft Silvery metals

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.

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.

Other Main Group Elements

Also Include Groups 3A-6A

All the elements in these groups are also considered Main Group Elements!

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.

Metals (Groups 1B-8B)

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

2) Inner Transition Metals

(Lanthanide and Actinide series)

Nonmetals

The nonmetals are mostly

bright colors. The ones that

are solid at room temperature

are brittle (can easily break).

Nonmetals are poor

conductors.

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)

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).

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

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)

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)

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)

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

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

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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