Download Developing Ideas about Matter

Survey
yes no Was this document useful for you?
   Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Document related concepts

Tennessine wikipedia, lookup

Chemical element wikipedia, lookup

Periodic table wikipedia, lookup

Unbinilium wikipedia, lookup

Ununennium wikipedia, lookup

History of molecular theory wikipedia, lookup

Transcript
Developing Ideas about Matter
Section A1.3
Objectives
describe examples of practical
applications of chemistry in food storage
 identify and explain early forms of
chemistry
 outline the development of our
understanding of the atomic model as
consisting of protons, neutrons and
electrons
 give examples of chemistry based careers
in the community

Review

Last class:
◦ Physical and chemical properties (what is the
difference? Examples?)
◦ What is the difference between a pure
substance and a mixture?
◦ What are signs of a chemical reaction? Which
ones did we see in the lab?
Back in the day…
People have been using chemical
properties of substances for centuries
 First Nations people had extensive
knowledge of plant use
 Our ancestors began to understand
relationship between temperature and
states of matter

Food Chemistry

How do physical changes apply to food?
Chemical changes? Examples?
◦ Physical changes: freezing (chemical
components stay the same)
◦ Chemical changes: baking (formation of new
substance)
Food Chem: Heating and Freezing

Heating- temporary sterilization
◦ Kills micro-organisms
◦ Canning- heat sterilization

Freezing- preserve almost indefinitely
◦ Prevents growth of micro-organisms
Salting
Way to preserve meat and fish
 Method of drying
 Draws water out of meat and bacteria
 Used by sailors

Fermentation
Biochemical preservation technique
 Bacteria convert starches and sugars into
alcohol & carbon dioxide; others into
acids

◦ Prevents growth of bacteria
◦ More digestible and higher vitamin content
◦ Helpful in preventing scurvy
More Early Chemistry

Metallurgy
◦ Producing and using metals
◦ Early peoples used gold, copper, silver, lead,
and iron
◦ Used copper for weapons by hammering it
into shapes
◦ Annealing- heating copper so not brittle when
hammered
Metallurgy continued…

Smelting- separating metal from other
elements in a compound
◦ Way to get copper
◦ Done in Egypt by 4000 B.C.

Alloy- mixture of metals
◦
◦
◦
◦
What is bronze an alloy of?
Tin and copper
Steel?
Iron and carbon
Aristotle and Matter
Aristotle thought matter composed of
combinations of fire, earth, water, and air
 Continuous (no such thing as a smaller
piece)
 Democritus- proposed tiny particles
(atomos)
 Didn’t test their ideas

Alchemy
Science and magic
 Experiments to turn cheap metals into
gold
 Many important scientific discoveries
made

◦ Mercury, procedures for making acids,
developed lab equipment
Atomic Theory
Theory: a major idea that explains a large
amount of data; based on many
experiments; may be changed when new
data is collected
 Atomic Theory: explains what the
structure of the atom is like

Developing Theories about Matter
Four classic models of atoms
 Examples of the scientific process
 Founded on experiments
 Dalton, Thomson, Rutherford and Bohr
 Modern model of the atom: based on
quantum mechanics

Atomic Models Activity: Jigsaw
In groups of 5, you will become “experts”
on a particular model of the atom
 You must teach the concept in a way to
answer the questions on the worksheet
and be useful to your fellow classmates
 You will teach your classmates about the
topic so be comfortable with it!

Atomic Models Activity:
Summary Chart
The Atom Chart
 While groups present fill in the chart

Dalton

Described atoms as small spheres,
different in size, mass, and color
depending on type
Thomson
Discovered the electron
 Experimented with beams of particles in a
vacuum tube
 Found that all elements produced the
same type of beam made of negative
charges
 Atoms made of smaller subatomic
particles in different combinations
 Electrons imbedded in positive sphere

Rutherford
Discovered the nucleus
 Gold foil experiment

◦ Shot positively charged particles at a thin piece of
gold foil
◦ Expected all particles to go right through, though
some deflected and some reflected right back
◦ Unexpected result: like firing a cannon ball at tissue
paper and having it bounce back!
◦ What does this mean?
◦ http://www.youtube.com/watch?v=Q8RuO2ekNGw
◦ http://www.youtube.com/watch?v=5pZj0u_XMbc&saf
ety_mode=true&persist_safety_mode=1&safe=active
Rutherford continued…

What this means:
◦ There is a strong, dense positively charged
core
◦ Called the nucleus
◦ Most of the atom empty space
◦ Nucleus very small (1/10 000 size of atom)
Bohr
Proposed that electrons surrounded
nucleus in specific energy levels
 Found evidence based on light released by
hydrogen atoms (gaps between energy
levels)
 Falling from higher to lower energy levels
releases particular color of light

Bohr continued…
Bohr continued …
Discovered every element has its own
unique pattern, and thus unique atomic
structure
 http://jersey.uoregon.edu/vlab/elements/El
ements.html

Quantum Mechanical Model of the
Atom
Electron cloud around nucleus
 Occupy whole space all at once at
different energy levels
 Nucleus contains nucleons

◦ Protons- positively charged
◦ Neutrons-no electrical charge