Science Reviewer PDF: Properties of Matter, Atoms, and Periodic Table

SCIENCE REVIEWER 1.Properties of matter. Matter – defined by its properties, characteristics and behavior. Properties – CHEMICAL or PHYSICAL and INTENSIVE or EXTENSIVE. CHEMICAL PROPERTIES – ability or inability of a substance to combine with another substance or change into a new substance. Always...

SCIENCE REVIEWER 1.Properties of matter. Matter – defined by its properties, characteristics and behavior. Properties – CHEMICAL or PHYSICAL and INTENSIVE or EXTENSIVE. CHEMICAL PROPERTIES – ability or inability of a substance to combine with another substance or change into a new substance. Always relates to a chemical change (chemical reaction) EXAMPLES: a. Reactivity – how does it react? b.Instability – tendency to breakdown into different substances. c. Toxicity – how poisonous/toxic d. pH – how acidic or basic e. Flammability – ease at which it will burn f. Melting point – temperature where a substance melts. PHYSICAL PROPERTIES – characteristics that can be measured/observed, doesn’t involve changes in composition EXAMPLES: a. Mass – amount of matter. (Mass = constant, Weight = measure of gravitational force) b. Volume – amount of space occupied. c. Color – ROYGBIV d. Texture – how it feels e. Hardness – quality of being hard (firm or solid) f. Malleability – ability to be hammered g. Elasticity – ability to return to its original position after being stretched. h. Ductility - ability to be drawn into a wire. i. Conductivity – ability to transfer heat, electricity or sound. j. Solubility – capacity to be dissolved k. Boiling point – vapor pressure is equal to the external pressure. l. Freezing point – liquid solidifies m. Density – mass per volume unit PROPERTIES OF MATTER a. Intensive properties – do not change with amount and can be used for identification. b. Extensive properties – constantly change and cannot be used for identification MATTER – takes up space and has mass, made of atoms. ATOMS – building blocks of matter. Too SMALL to be seen (ANGSTROM – unit of length equal to one ten millionth of a milimetre). MOLECULE – particle consisting of 2 or more atoms combined in a certain arrangement GAS – particles move at random directions very QUICK and travel in a straight-line path. When gas is in the container, it take the shape of the container. LIQUID – particles move and change locations but not as freely as gas. SOLID – particles are held together, have definite shapes and volume. 2. Phase change a. Evaporation – liquid to gas (cooling process) b. Condensation – gas to liquid c. Melting – solid to liquid d. Freezing – liquid to solid e. Sublimation – solid to gas f. Deposition – gas to solid 3. Atoms ATOMS – electrically neutral, but carry electrically charged particles. PROTONS – positive. ELECTRON – negative, lightest. NEUTRON – neutral, heaviest. DEMOCRITUS AND LEUCIPPUS believed that nature consists of 2 things, atoms and the void. Atomos – indivisible particle a. Democritus – believed that atoms were uniform, solid, hard, incompressible, and indestructible but Aristotle rejected this idea and said that the world is composed of air, fire, earth, and water. b. John Dalton (1803) – envisioned atoms as solid, hard spheres, and used wooden balls to model them. Model: Solid sphere/billiard ball/bowling ball model c. JJ Thomson (1904) – discovered electron. Model: Plum pudding model d. Ernest Rutherford (1911) – discovered proton while performing the ALPHA PARTICLE SCATTERING EXPERIMENT. Model: Nuclear model. e. Neils Bohr (1913) – electrons encircle the nucleus of the atom in a specific path called ORBITS. Model: Planetary/Bohr model. f. Erwin Schrodinger (1926) – used mathematical equations to describe the likelihood of finding the electron in a certain position. Model: Quantum mechanical model. g. James Chadwick – discovered neutron Elements in periodic table was arranged based on: a. Atomic number b. Electronic configuration c. Recurring chemical properties Atomic # = # of protons # of protons = # of electrons (atoms in their most stable state are neutral, “neutral atom” Charge = # of protons - # of electrons Positive charge – minus. Negative charge – add ISOTOPES – atoms belonging to the same element, thus, having the same number of protons but different number of neutrons. MASS # - distinguishes an isotope of a particular element to its other isotopes Mass # = # of protons + # of neutrons # of neutron = mass # - atomic # (# of proton) MASS NUMBER – sum of the # of protons and neutrons ATOMIC MASS/ATOMIC WEIGHT – weighted ave. mass of an atom 4. Periodic table a. Johann Wolfgang Dobereiner (1829) – identified groups of 3 elements with similar properties (triads) b. John Newlands (1863) – arranged the periodic table with increasing order of atomic masses. Every 8th elements had similar properties and called this law of octaves. (Newlands Octaves) c. Dmitri Mendeleev (1869) “Father of the Periodic Table” – created the framework. Believed that atomic mass was the most fundamental property in classifying the elements. He predicted the properties of some undiscovered elements and gave them names such as “eka-aluminium” for an element with properties similar to aluminium. MENDELEEV’S LAW – the physical and chemical properties of elements are a periodic functions of their atomic masses. d. Henry Moseley (1913) – atomic number is the most fundamental property of an element and not atomic mass. MODERN PERIODIC LAW – the chemical and physical properties of an elements are a periodic function of their atomic number. 5. Trends in Periodic table PERIOD – horizontal row (1-7) GROUPS/FAMILIES – vertical columns (1-18) ATOMIC RADIUS – distance from an atom’s nucleus to the outermost orbital of electrons. (Left to right – decreases, top to bottom – increases) IONIC RADIUS – distance from the nucleus of an ion up to which it has an influence on its electron cloud. (Left to right – decreases, top to bottom – increases) IONIZATION ENERGY – energy absorbed by an atom to remove electron. Higher – harder to lose an electron. (Left to right – increases, top to bottom – decreases) ELECTRON AFFINITY – energy released by an atom to gain electron. (Left to right – increases, top to bottom – decreases) ELECTRONEGATIVITY – general tendency of an atom to attract electrons towards itself. Higher – chance of attracting electrons. METALLIC PROPERTY – general tendency of an atom to lose electrons. More metallic – more easily it lets go of its electron. NONMETALLIC PROPERTY – how easy it is for an atom to gain an electron METALLIC CHARACTER -. (Left to right – decreases, top to bottom – increases) NONMETALLIC CHARACTER - (Left to right – increases, top to bottom – decreases) REACTIVITY OF A METAL – elements ability to ionize or share electrons. More reactive – gain/lose. Less reactive – share. Less reactive metal CANNOT replace a more reactive metal. (no reaction) More reactive metal CAN replace a less reactive metal (produce a reaction)