Week 5 – Physical & Chemical Change, Flame Tests, Evidence of Chemical Reactions (Lab Class)

Bachelor of Science in Medical Technology (1st Year): INORGANIC AND ORGANIC CHEMISTRY

• the study of matter and the changes it undergoes. These changes can be broken down into two classes—physical changes and chemical changes.

Chemistry

• one or more physical properties of a substance are altered.

• include size, shape, color, and physical phase (solid, liquid, or gas). Grinding, melting, dissolving, and evaporating

Physical change

• results in the formation of one or more “new” substances.

• These new substances differ in chemical properties and composition from the original substance.

• The rusting of iron and the burning of paper are two examples of chemical change.

chemical change

• an insoluble solid that emerges from a liquid solution.

• The emergence of the insoluble solid from solution.

Precipitate

• the formation of gas bubbles in a liquid by a chemical reaction.

• release of carbon dioxide which bubbles as a gas from the liquid when limestone chips, which are composed of calcium carbonate, are added to dilute hydrochloric acid.

Effervescence

• process resulting from random motion of molecules by which there is a net flow of matter from a region of high concentration to a region of low concentration.

• example is the perfume of a flower that quickly permeates the still air of a room.

Diffusion

• Who theorizedthat electrons have specific energy values, which he called energy levels.

Bohr

• a procedure used to test qualitatively for the presence of certain metals in chemical compounds.

flame test

• This technique, Flame Test, of using certain chemical compounds to color flames is widely used in ________ to produce the range of colors seen in a firework display.

pyrotechnics

• absorbs the yellow light given off by sodium while letting most other wavelengths of light pass through.

cobalt glass

• the range of frequencies of electromagnetic radiation and their respective wavelengths and photon energies.

• energy is proportional to frequency, while frequency is inversely proportional to wavelength.

Electromagnetic Spectrum

• a particular type of electromagnetic radiation that can be seen and sensed by the human eye, but this energy exists at a wide range of wavelengths.

Light

• the basic unit for measuring the wavelength of electromagnetic waves.

micron

• The shortest waves are __________, which have wavelengths of 10e- 6 microns or less.

gamma rays

• The longest waves are ________, which have wavelengths of many kilometers.

radio waves

• the portion of the electromagnetic spectrum that is visible to the human eye.

• A typical human eye will respond to wavelengths from about 380 to 740 nanometers.

Visible Spectrum

Identify the color of the wavelength (nm):

• 400-430 (30)

Violet

Identify the color of the wavelength (nm):

• 430-490 (60)

Blue

Identify the color of the wavelength (nm):

• 490-560 (70)

Green

Identify the color of the wavelength (nm):

• 560-580 (30)

Yellow

Identify the color of the wavelength (nm):

• 580-620 (40)

Orange

Identify the color of the wavelength (nm):

• 620-800 (80)

Red

• is the gas state of water and is also called water vapor.

Steam

• the process that takes place when a substance (or substances) is brought into contact with each other and produce a new substance(s).

Chemical Reaction

• The substance (or substances) initially involved in the chemical reaction are called

reactants or reagents.

• are balanced to show the same number of atoms of each element on each side.

Chemical equations

• states that matter cannot be created nor destroyed. What this means is that even though different substances are created during the process of a chemical reaction, none of the reactant atoms are lost.

• They are simply rearranged into the new substances.

Law of Conservation of Mass

• any process which requires or absorbs thermal energy from its surroundings, usually in the form of heat.

Endothermic

• describes a process or reaction that releases energy from the system to its surroundings, usually in the form of heat, but also in a form of light, electricity, or sound.

Exothermic