Matter --- Properties and Changes 2017 – 2018

Properties of Matter Matter is anything that has mass and takes up space. Matter with a uniform and unchanging composition is called a substance. Examples: Air, microbes, table salt (sodium chloride), and pure water.

States Of Matter States of matter is the physical form of a substance. Solid: Has its own definite shape and volume. Examples: Wood, iron, paper, and sugar. Liquids: Matter that flows, has constant volume, and takes the shape of its container. Examples: water, blood, and mercury. Gases: Matter that not only flows to conform to the shape of its container but also fills the entire volume of its container. Vapor: is the gaseous state of a substance that normally exists as a solid or a liquid in its natural state.

Physical Properties of Matter A physical property is a characteristic of matter that can be observed or measured without changing the sample’s composition. Extensive properties: are dependent on the amount of substance present. Example: Mass, length, and volume. Intensive properties: are independent of the amount of substance present. Example: Density.

Chemical Properties of Matter The ability or inability of a substance to combine with or change into one or more other substances.

Changes in Matter Physical Changes: A process that alters a substance without changing its composition. Examples: breaking, cutting, grinding, and ripping. Phase change: is a transition of matter from one state to another. Examples: boil, freeze, condense, vaporize, or melt in chemistry generally refer to a phase change in matter.

Chemical Changes Chemical change: A process that involves one or more substances changing into new substances. Signs of a Chemical Reaction: Heat is given off or absorbed. Light is given off. Gas or precipitate is formed. Color change not due to moister loss or gained. Odor change. Change is not easily reversed.

Law of Definite Proportions Law of Proportions states that a compound is always composed of the same elements in the same proportion by mass, no matter how large or small the sample. Percent by mass is the ratio of the mass of each element to the total mass of the compound expressed as a percentage. Percent by mass(%) = mass of element/mass of compound X 100

Law of Multiple Proportions The law of multiple proportions states that when different compounds are formed by a combination of the same elements, different masses of one element combine with the same fixed mass of the other element in a ratio of small whole numbers. Examples: H2O, H2O2

The Roots of Atomic Theory Democritus (460 – 370 B.C.) Matter is composed of atoms, which move through empty space. Atoms are solid, homogeneous, indestructible, and indivisible. Different kinds of atoms have different sizes and shapes. Size, shape, and movement of atoms determine the properties of matter.

Aristotle (384 -322 B.C.) Empty space cannot exist. Matter is made of earth, fire, air, and water.

Dalton’s Atomic Theory Matter is composed of extremely small particles called atoms. Atoms are indivisible and indestructible. Atoms of a given element are identical in size, mass, and chemical properties. Atoms of a specific element are different from those of another element. Different atoms combine in simple whole-number ratios to form compounds. In a chemical reaction, atoms are separated, combined or rearranged.

Conservation of mass The mass of the reactants equal the mass of the products in any chemical reaction.

The Atom The smallest particle of an element that retains the properties of the element Made up of protons, electrons, and neutrons.

J. J. Thomson Experiment: Cathode ray tube (1897) Discovered electron!!! Electron is negatively charged Measured charge-to-mass ratio of electron

J. J. Thompson

Thomson’s Model: Plum Pudding

Robert Millikan Experiment: Oil drop experiment (1909) Measured charge of electron Both charge of electron and charge-to-mass ratio were used to determine the mass of an electron Mass of electron is 1/1837 mass of hydrogen atom (essentially massless)

Billiard Ball Plum Pudding Planetary Model

Robert Millikan

Discovery of the Nucleus

Ernest Rutherford Experiment: Gold foil experiment Discovered nucleus!!!! All mass of an atom is in the nucleus Nucleus is VERY massive

Ernest Rutherford

Rutherford’s model of the atom Planetary Model

Billiard Ball Plum Pudding Planetary Model

John Dalton JJ Thompson Robert Milikan Ernest Rutherford   JJ Thompson Robert Milikan Ernest Rutherford

Brian Cox – Gold Foil http://www.youtube.com/watch?v=wzALbzTdnc8 Cathode Ray: http://www.youtube.com/watch?v=IdTxGJjA4Jw

The Periodic Table Mass Atomic mass unit (amu): One-twelfth the mass of a carbon-12 atom. Masses of subatomic particles Charge Mass Relative Mass Relative Charge Proton 1 1.673 X10-24 1+ Electron - No Mass 1/1840 1- Neutron No Charge 1.675 X10-24

Atomic Number Atomic Number: The number of protons in the atom. Because the atom is neutral in charge it is also the number of electrons in the atom. (Average) Atomic Mass: of an element is the weighted average mass of the isotopes of that element. Examples:

Mass Number Mass number is the sum of the atomic number (or number of protons) and neutrons in the nucleus. Mass Number = atomic number + number of neutrons

Isotopes Isotopes: Atoms with the same number of protons but different numbers of neutrons. Examples:

Examples: Calculating Atomic Mass Isotope Abundance for Element X Calculate the atomic mass of element X Isotope Mass(amu) Percent Abundance 6X 6.015 7.59% 7X 7.016 92.41%

Calculate the atomic mass of element X and identify the element from the periodic table knowing that it has the following isotopes: 54 X (mass: 53.940, abundance: 5.9%), 56 X (mass: 55.935, abundance: 91.72%), 57 X (mass: 56.935, abundance: 2.1%), and 58 X (mass: 57.933, abundance: 0.28%)

Notation Hyphen Notation (name): Name-mass number Examples: Nuclear Notation (Symbol)

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