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What is chemistry?
The study of science composition, structure, property and reaction of matter especially in atomic and molecular level systems.
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What is matter?
Anything that has mass and occupies space.
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Pure substance
- are categorized into (element and compound)
- a pure substance always has a definite composition by mass.
- example of elements are cooper, gold and oxygen.
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Element
- is a substance that cannot be broken down by chemical means to simpler substance.
- Ex. of Noble metals:
- Au=gold, Ag= silver, Ag=platinum, Pt=platinum
- Cu=Cooper
- Ex. Noble gases
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Compound
- distinct substance that contains 2 or more elements chemically combined in a definite proportion by mass. Can be decomposed chemically into simpler substance ex.
- H2SO4 =Sulfic Acid/ H2O= water
- HCl=Hydro Chloric Acid
- NaCl= Sodium Chloraide
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Mixture
always contains 2 or more substance that can be present in varying amounts. The components of a mixture do not lose their identities and may be separated by physical means.
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Homogeneous mixture
- uniform in appears(looks the same)
- ex. saline solution= NaCl, cant tell that water has salt once you boil it, salt is left is over.
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Heterogeneous
- able to tell difference (has residual) in mixture of drink, ex. Coffee,Koolaid,
- anything bigger 1<nm = 10.9 is affected by gravity, so it will seattle to the bottom and can tell the difference.
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Metals
- are solids at room temperature (mercury is an exception)
- high luster
- Good conductors of heat and electricity
- malleable
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Nonmetals
- unlike metals, are not lustrous
- poor conductors of heat and electricity
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Metalloids
have properties that are intermediate that contain both metals and nonmetals, this are semiconductors
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Molecular
- smallest uncharged individual unit of compound formed by the union of 2 or more atoms.
- Water is a typical molecular compound.(H2O)
- this molecular cannot be further subdivided w/o
- destroying the water molecule and forming hydrogen and oxygen.
- Molecular has (non metal+non metal)
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Ion
- is a positively and negatively charged atom or group of atoms. Is held together by the attrition forces that exist between positive and negative charge ions.
- cation (cat-eye-on) is a positively charged ion
- anion (an-eye-on) is a negatively charged ion
- Ion compound is (metal +non metal) NaCl =0
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Physical properties
- are inherent characters of a substance that can be determined w/o altering its composition.
- color, taste, odor, state of matter, density,
- melting point, boiling point
- changes the structure of object but not the chemical ex. ice to water to gas
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Chemical properties
- describes the ability of substance to form a new substance either by reaction with other substance or by decomposition
- ex. Rust on metal
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Physical Changes
- are changes in physical properties (such as size, shape and density) or changes in state of matter w/o change in composition ex. H2O
- ice to water to gas
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chemical change
- a change producing producing products that differ in composition from the original substance change the chemical structure and the way it looks.
- ex. H2 + O2 = H2O
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law of conservation of mass
Energy can be neither created nor destroyed though it can be transformed from one to another
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Energy
the ability of matter to work
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potential energy
stored energy, energy that an object possesses due to it relative position
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Kinetic energy
- released energy, is energy that matter possesses due to its motion.
- ex. when water behind is released and allowed to flow, its potential energy is changed to kinetic energy.
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