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Welcome to the World of Chemistry. The Language of Chemistry. CHEMICAL ELEMENTS - pure substances that cannot be decomposed by ordinary means to other substances. Aluminum. Bromine. Sodium. The Language of Chemistry.

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the language of chemistry
The Language of Chemistry
  • CHEMICAL ELEMENTS -
    • pure substances that cannot be decomposed by ordinary means to other substances.

Aluminum

Bromine

Sodium

the language of chemistry3
The Language of Chemistry
  • The elements, their names, and symbols are given on thePERIODIC TABLE
  • How many elements are there?
the periodic table
The Periodic Table

Dmitri Mendeleev (1834 - 1907)

glenn seaborg 1912 1999
Glenn Seaborg(1912-1999 )
  • Discovered 8 new elements.
  • Only living person for whom an element was named.
copper atoms on silica surface see cd rom screen 1 4
Copper atoms on silica surface.See CD-ROM Screen 1.4
  • An atomis the smallest particle of an element that has the chemical properties of the element.

Distance across = 1.8 nanometer (1.8 x 10-9 m)

slide7

Electron cloud

Nucleus

The Atom

An atom consists of a

  • nucleus
    • (of protonsand neutrons)
  • electrons in space about the nucleus.
slide8

The red compound is composed of• nickel (Ni) (silver)• carbon (C) (black)• hydrogen (H) (white)• oxygen (O) (red)• nitrogen (N) (blue)

CHEMICAL COMPOUNDSare composed of atoms and so can be decomposed to those atoms.

slide9
AMOLECULEis the smallest unit of a compound that retains the chemical characteristics of the compound.

Composition of molecules is given by aMOLECULAR FORMULA

C8H10N4O2 - caffeine

H2O

the nature of matter
The Nature of Matter

Chemists are interested in the nature of matter and how this is related to its atoms and molecules.

Gold

Mercury

chemistry matter
Chemistry & Matter
  • We can explore the MACROSCOPIC world — what we can see —
  • to understand the PARTICULATE worlds we cannot see.
  • We write SYMBOLS to describe these worlds.
a chemist s view of water
A Chemist’s View of Water

Macroscopic

H2O

(gas, liquid, solid)

Symbolic

Particulate

a chemist s view
A Chemist’s View

Macroscopic

2 H2(g) + O2 (g)

--> 2 H2O(g)

Particulate

Symbolic

kinetic nature of matter
Kinetic Nature of Matter

Matter consists of atoms and molecules in motion.

states of matter
STATES OF MATTER
  • SOLIDS— have rigid shape, fixed volume. External shape can reflect the atomic and molecular arrangement.
    • Reasonably well understood.
  • LIQUIDS— have no fixed shape and may not fill a container completely.
    • Not well understood.
  • GASES— expand to fill their container.
    • Good theoretical understanding.
physical properties
Physical Properties

What are some physical properties?

  • color
  • melting and boiling point
  • odor
physical changes
Physical Changes

Some physical changes would be

  • boiling of a liquid
  • melting of a solid
  • dissolving a solid in a liquid to give a homogeneous mixture — a SOLUTION.
density an important and useful physical property

Platinum

Mercury

Aluminum

DENSITY - an important and useful physical property

13.6 g/cm3

21.5 g/cm3

2.7 g/cm3

slide21
Problem A piece of copper has a mass of 57.54 g. It is 9.36 cm long, 7.23 cm wide, and 0.95 mm thick. Calculate density (g/cm3).
slide22
Strategy

1. Get dimensions in common units.

2. Calculate volume in cubic centimeters.

3. Calculate the density.

slide23
SOLUTION

1. Get dimensions in common units.

2. Calculate volume in cubic centimeters.

3. Calculate the density.

(9.36 cm)(7.23 cm)(0.095 cm) = 6.4 cm3

Note only 2 significant figures in the answer!

problem mercury hg has a density of 13 6 g cm 3 what is the mass of 95 ml of hg in grams in pounds
PROBLEM: Mercury (Hg) has a density of 13.6 g/cm3. What is the mass of 95 mL of Hg in grams? In pounds?

Solve the problem using DIMENSIONAL

ANALYSIS.

problem mercury hg has a density of 13 6 g cm 3 what is the mass of 95 ml of hg
PROBLEM: Mercury (Hg) has a density of 13.6 g/cm3. What is the mass of 95 mL of Hg?

First, note that 1 cm3 = 1 mL

Strategy

1. Use density to calc. mass (g) from volume.

2. Convert mass (g) to mass (lb)

Need to know conversion factor

= 454 g / 1 lb

problem mercury hg has a density of 13 6 g cm 3 what is the mass of 95 ml of hg26
PROBLEM: Mercury (Hg) has a density of 13.6 g/cm3. What is the mass of 95 mL of Hg?

1. Convert volume to mass

2. Convert mass (g) to mass (lb)

slide27

There’s more?

Observations!

chemical properties and chemical change
Chemical Properties and Chemical Change
  • Burning hydrogen (H2) in oxygen (O2) gives H2O.
  • Chemical change or chemical reaction — transformation of one or more atoms or molecules into one or more different molecules.
types of observations and measurements
Types of Observations and Measurements
  • We make QUALITATIVE observations of reactions — changes in color and physical state.
  • We also make QUANTITATIVE MEASUREMENTS, which involve numbers.
  • Use SI units — based on the metric system
units of measurement
UNITS OF MEASUREMENT

Use SI units — based on the metric system

Length

Mass

Time

Temperature

Meter, m

Kilogram, kg

Seconds, s

Celsius degrees, ˚C

kelvins, K

units of length

O—H distance =

9.4 x 10-11 m

9.4 x 10-9 cm

0.094 nm

Units of Length
  • 1 kilometer (km) = ? meters (m)
  • 1 meter (m) = ? centimeters (cm)
  • 1 centimeter (cm) = ? millimeter (mm)
  • 1 nanometer (nm) = 1.0 x 10-9 meter
temperature scales

Anders Celsius

1701-1744

Lord Kelvin

(William Thomson)

1824-1907

Temperature Scales
  • Fahrenheit
  • Celsius
  • Kelvin
temperature scales33

212 ˚F

100 ˚C

373 K

100 K

180˚F

100˚C

32 ˚F

0 ˚C

273 K

Temperature Scales

Fahrenheit

Celsius

Kelvin

Boiling point of water

Freezing point of water

Notice that 1 kelvin degree = 1 degree Celsius

temperature scales34
Temperature Scales

100 oF

38 oC

311 K

oF

oC

K

calculations using temperature
Calculations Using Temperature
  • Generally require temp’s in kelvins
  • T (K) = t (˚C) + 273.15
  • Body temp = 37 ˚C + 273 = 310 K
  • Liquid nitrogen = -196 ˚C + 273 = 77 K
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