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Matter: Properties and Theories
Transcript of Matter: Properties and Theories
The Models of the Atom
Matter: Properties and Theories
Sir Joseph John Thomson best known as J..J. Thomson, discovered the electron in series of experiments designed to study the nature of electric discharges in a high-vaccum cathode-ray tube. His theory stated that the atom not a neutral body; rather it containing charges of subtomic particles, such as protons and electrons.
Ernest Rutherford started working on radioactive substances with J.J. Thomson in England. Rutherford did his research at McGill University, where he performed an experiment that led to the discovery of the nucleus of the atom. His theory was that an atom is basically empty space through which the positive particles can pass through, but each atom was a tiny,positively charged core.
This Danish physicist worked under the hand of Ernest Rutherford in England. He thought that electrons surrounded the nucleus in specific energy levels. His evidence was found as he examined the light which released hydrogen atoms which are made to glow in a tube. Bohr's experiments also explained why negative charges do not merge with the positively charges in the nucleus. That reason is because electrons can't fall below the lowest of energies. Thus said an electron can't fall into a nucleus under normal circumstances.
by: Hazel Mae Duenas
Classifiation of Matter
Matter is anything that occupies space or has mass
Mixtures are pure substances that are mixed together .
All of the particles that make up a substance are the same, this means that the chemical and physical properties never change or are constant.
John Dalton was a physicist as well as a chemist. His theory was based on the premise that the atoms of different elements which could be distinguished by diffences in weight. This is the model used to explain his theory.
- Atoms are made of small, indivisible particles
- All atoms of an element are identical in properties like size and mass
- Atoms properties are different if the atoms are in different elements
- Atoms of different elements can combine in specific fixed ratios to form new substances
The Quantum Mechanical Model of the Atom
In today's model of the lovely atom, the atom is now based on a theory we like to call quantum mechanics. Its use of mathematical probability describes how electrons exist in atoms. Electrons can be thought as a "cloud" of negative charge, instead of a tiny negative particle. Rather than thinking as a small particle moving quickly through space, like Mr. Bohr, his theory was abandoned. Instead, the electrons take up all the space at once at different energy levels. The electron cloud surrounds a nucleus containing two types of particles. They're called nucleons. They're a proton and a neutron. The proton has a positive charge, as on the other hand neutrons have no electrical charge .
A compound is a chemical combination of two or more elements. I.E NaOH2 CO2
An element is made up of just one atom. I.E gold, helium, hydrogen.
A heterogeneous mixture because you cam see the different particles in the mixture. I.E soil
A solution is a homogeneous mixture because two or more substances are mixed and they look like one. I.E soft drink
A suspension is a form of a mechanical mixture, the catch is that both substances that are together have to be in a different state. I.E a sandstorm in the desert sand(solid) air(gas)
A colloid is very similar to a suspension but the two substances can't be to easily taken apart.
Theories about Matter,
applications of Food Chemistry and Metallurgy
by: Irvin Taguiam
Was a greek philosopher and scientist, born
in 384 bc and died in 322 bc.
His theory was "matter is composed of combinations of fire, earth, water and air, he thought that these 4 elements were continuous which meant that there was no such thing as a smallest piece.
Is a combination of science and magic, it
is not real science but it contributed to the development of chemistry. However since alchemists would not share information with other alchemists it would sometimes take years to rediscover an alchemists discovery when
they passed away.
Alchemists - people who perform alchemy,
they began to debate if the "atomos" propsed
by "Democritus" thousands of years earlier
existed. They called these tiny particles
Another greek philosopher that propsed
"matter was made up of tiny particles that
could not be divided into smaller pieces,
he called them "atomos" meaning indivisible
Physical and Chemical techniques that
have been known for thousands of years.
This includes drying, heating, freezing, fermentation and chemical preservation.
Types of changes
When the chemical components remain
the same, no new substance is formed, freezing is a type of physical change.
Always results in the formation of different substances.
Heating food temporarily sterilizes it.
Sterilization, is any process that kills micro
Canning - involves heat sterilization followed by sealing in an oxygen free temperature.
Another physical process that can preserve food almost indefinitely.
The very low temperature prevents the
growth of micro-organisms that cause decay.
A method of preserving meat and fish and is actually a method of drying.
The salt draws water out of bacteria, either
killing them or making them inactive.
This was used by sailors before other preservation
techniques for meat was made.
Was made, because when food was preserved
certain nutrients such as vitamin C was not always
retained. Leading to what sailors called scurvy.
Captain cook discovered that pickled cabbage had a high vitamin C content, and was produced by this process.
This is a biochemical preservation technique involving
bacteria called "Lactobacilli.
Converts starches and sugars present in fruits and vegetables into a chemical called lactic acid.
Lactic acid is a preservative that presents the growth of bacteria that caused food to rot.
Lactobacilli bacteria are beinificial to food because they
make it more digestible and increase vitamin levels.
Was a commonly used food preservation technique and is still used today.
Smoking introduces chemicals called antioxidants taht show the rotting process.
Wood smoke contains formaldehyde, which acts as a preservative.
The science of using and producing metals.
The early uses of copper relied on native copper, copper however occurs this way only in small amounts.
Copper is much more common in compounds with other elements, however copper in compounds was unusable until smelting technology was created.
A process of extractive metallurgy, its main use is to produce a base metal from its ore.
Is the heating of copper before it is hammered. Annealing changed the metal, so it was no longer brittle when hammered.
With this discovery, copper could be hammered into sheets and made into stronger tools and weapons.
The only known metals were gold, copper, silver, lead and iron.
A discovery of tin ores caused a revolution in metallurgy the Sumerians. in the middle east had begun smelting tin ores with copper ore.
Discovered that the metal produced from this combination was much easier to cast than pure copper because it flowed more easily and was much stronger.
The copper and tin formed an alloy called bronze.
Alloy is a mixture of any metals.
Bronze made much stronger tools and weapons than either copper or tin alone.
A process for smelting iron was created.
Iron Age began.
Developed industrial, agricultural technology.