Introductory Chemistry

Chemistry
The study of Matter and the energy associated with chemical and physical changes in matter
Matter
Anything in Universe that has Mass and occupies space
Element
Element is a pure substance that is composed of only one kind of atom. The atoms may be combined to form molecules. As long as all of the atoms are the same, the substance is an element. The sample may be a solid, a liquid, gas, or a mixture of states. Elements are the simplest form of matter and cannot be broken down by physical or chemical changes
Compound a compound is
a pure substance that is composed of two or more elements. All of the molecules in a pure substance is the same. The sample may be a solid, a liquid, a gas, or a mixture or states can be decomposed into other compounds by chemical changes—compound always two names
Mixture-
physical combination of two or more solutions
Mixture heterogenus
(1) two or more visible phases (2) different properties in different phases
Mixture homogenus
Uniform (1) one visible phase (2) same properties throughout
Solvent
dissolving medium
Solute
substance dissolves in the solvent
Solubility
the extent to which a given solute dissolves in a given solvent
Physical change—
a new form of the substance
Chemical Change
a change that makes something new with new chemical formula and its own unique composition and properties
Law of conservation of Mass
In a physical or chemical change, mass is neither created nor destroyed 1774 Antoine Lavoisier
Energy-
capacity to move matter or produce change in matter
Potential Energy
Energy that is stored in object or in position (1) Gravitational (2)Electrostatic stored in molecules..like charges repelled(3) chemical(bonds broken energy released)
Kinetic Energy
Energy of Motion KE= ? mv2
List of forms of Energy
1.Mechanical- depends on the position or motion of object 2 Electrical associated with movement of electrons or storage of charge 3. Heat Thermal motion of particles; depends on (a) temperature (b) amount of substance 4. chemical relased or exchanged during rxns (a) endothermic (b) exothermic 5. Radiant associated with Radiation 6. Nuclear associated with changes in Nuclei
Law of Conservation of Energy
In a physical or chemical change, energy is neither created or destroyed. It is converted form one form to another
Daltons Atomic Theory
1. Each element is made up of tiny, individual particles called atoms
2. Atoms are indivisible; they cannot be created or destroyed
3. All atoms of each element are identical in every respect
4. Atoms of one Element are different from atoms of any other element
5. Atoms of one element may combine with atoms of other elements, usually in ratio of small whole numbers, to form chemical compunds
Law of Multiple Proportions
when two elements combine to form more than one compound, the different weights of one element that combine with the same weight of the other element are in a simple ratio of whole numbers
Modifications to Dalton
1. Atoms can be subdivided into sub-atomic particles
2. atoms of some particles can have different masses—isotopes (different number of neutrons
3. some compounds are formed in large whole number ratios
4. we can change one element into another using nuclear reactions
Faraday & Crookes 1820
discover the electron
Thomson 1897
discovers electron has a negative charge comes up with raisin bran model as opposed to Dalton billiard ball model
Rutherford 1919
discovers proton with positive charge
Chadwick 1932
discovers neutron with no charge
The nuclear model of the Atom
Rutherford
1. Every atom contains an extremely small extremely dense nucleus
2. all of the positive charge and nearly all of the mass of an atom are concentrated in the nucleus
3. Then nucleus is surrounded by a much larger area of empty space that makes up the rest of the atom
4. The space outside the nucleus is very thinly populated by electrons , the total charge of which exactly balances the positive charge of the nucleus
Plonium
alpha source = 2p+2n
Isotopes
Atoms of the same element that have a different atomic mass
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