Atomic Structure PDF
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This document discusses atomic structure, including subatomic particles, isotopes, and the structure of an atom. It covers topics like protons, neutrons, electrons, and the nucleus. It also briefly touches upon chemical concepts like atoms and molecules.
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Isotope Atomic Structure - Atoms of the same element with different number of neutrons. Subatomic Particles STRUCTURE OF AN A...
Isotope Atomic Structure - Atoms of the same element with different number of neutrons. Subatomic Particles STRUCTURE OF AN ATOM - Super-small particles can be found - Every atom is made of a nucleus with inside the pieces of atoms protons and neutrons. - Include nucleus and quarks. - Contains alpha and beta particles. Nucleus - The Bohr model shows the three basic - Surrounded by electrons. subatomic particles in a simple manner. - All positive charge of an atom is in the PARTS OF AN ATOM nucleus and originates from protons. - Discovered by Ernest Rutherford. Electrons - Outside of the nucleus is empty. Protons Neutrons Protons & Electrons - Oppositely charged. Protons & Neutrons - Has the same mass. - In the nucleus which is the center of an atom. Atom Electrons - Contains protons and neutrons, and - Has a small mass and found on the surrounded by electrons. edges of an atom - Neutral overall charge since it has the - Discovered by John Joseph Thomson in same number of electrons and protons. 1897. - All substances are made of atoms. - Usually taken as zero and has a negative - Atoms → Molecules → Particles → charge. Matter - It is located in the electron channel - Democritus started the theory about (represents the area around an atom's atoms. nucleus where electrons are most likely - Most of its mass is in the nucleus – a to be found. It is a sphere that small, dense area at the center of every surrounds the microscopic nucleus). atom. - Symbol is e- Atomic Number - Has a mass of 9.109 410 x 10⁻²⁸ gram which is relatively equal to.0005486 - Number of protons. amu. - The elements are arranged in the - The mass is about 1/1837 that of the periodic table in ascending order of highest atom hydrogen. atomic number. Protons - Smallest particle in a chemical element or compound that has the chemical - Discovered by Ernest Rutherford 1919. properties. - Has a positive charge. - Made of atoms held together by - Has a mass of 1.673 x 10⁻²⁴ gram and chemical bonds. relative mass is 1.0073 amu. - Distinguished from ions by their lack of - Symbol is p+ electrical charge. Neutrons - Derived from the Latin word “moles” meaning small unit of mass. - Equal to the mass of protons and relative mass is 1.0087. Homonuclear Molecule - Has a neutral charge. - Consists of one chemical element, as - Discovered by James Chadwick in 1932 with oxygen. which he demonstrated that it penetrates radiation incorporated Heteronuclear Molecule beams of neutral particles. - Chemical compound composed of more - Located in the nucleus with the protons. than one element, as with water. - Number of neutrons is called neutron number. Hydrogen Bond & Ionic Bond - The neutrons in an element determine the isotope of an atom and often its - Atoms and compounds connected by stability. non-covalent interactions. - Number of neutrons is not necessarily - Not considered single molecules. equal to the number of protons. Covalent Bonds - Symbol is no - Chemical bond that involves the sharing of electron pairs between atoms. Molecule Trends and the Periodic Table Trends - More than 20 properties change in predictable way-based location of elements on PT. - Some properties: >Density > Melting point/boiling point PERIOD ELEMENT CONFIGURATION >Atomic Radius >Ionization Energy 1 H 1 >Electronegativity 2 Li 2–1 3 Na 2–8–1 Reactivity of Non-metals 4 K 2–8–8–1 - Judge reactivity of non-metals by how 5 Rb 2 – 8 – 18 – 8 – 1 6 Cs 2 – 8 – 18 – 18 – they easily gain electrons. 8–1 HOW DO YOU KNW IF N ATOM GAINS OR 7 Fr 2 – 8 – 18 – 32 – LOSES ELECTRONS? 18 – 8 - 1 ❖ Increasing # energy levels as we Think of Lewis Structure of ions. go down. Atoms form ions to get valence of 8 (or 2 for H). Atomic Radius Metals tend to have 1, 2, or 3 - ½ distance between neighboring nuclei valence electrons. in molecule or crystal. >Easier to lose them. - Affected by: Nonmetals tend to have 5, 6, 7 valence electrons. >Amount of energy levels >Proton >Easier to add them. pulling power Noble gases already have 8 so they Ionization Energy don’t form ions easily. - Amount of energy required to remove a CATIONS ANIONS valence electron from an atom in gas - Positive - Negative phase ions ions - Non-metals have a greater ionization - Formed - Formed energy since they can increase their by loss of by gain stability by gaining electrons to become electrons of. electrons anions. - Always. 1st Ionization Energy smaller - Always than larger - Energy required to remove the most parent than loosely held valence electron (farthest atom. parent from nucleus). atom. Allotropes Electronegativity - Different forms of elements in same - Ability of an atom to attract electron in phase – different structures and bond. properties. - Noble gases tend to not form bonds, so - O2 and O₃ are gas phases they don’t have electronegativity. > O2 → Oxygen and necessary to life - Unit = Pauling > O₃ → Ozone and is toxic to life. >Fluorine is the most electronegative - Graphite and diamonds are both carbon element which has 4.0 Paulings. in solid form. Reactivity of Metals - Judge reactivity of metals by how easily they give up electrons. Chemical Names and Formulas Metals and Non-metals - Stairway of Division on periodic table. - C, P, Se, I, Rn, and to the right are non- metals. - B, Si, As, Ge, Sb, Te, Po, Al are semi- metals. - The rest are metals. Ionic Compounds - Composed of positive and negative ions. - Formed from a metal and non-metal. - Not too attached to one another. - Examples are: NaCl, CaBr₂, and Kl. Naming Compounds - Recognizing whether a compound is ionic or molecular. Binary Ionic Compounds - 1ST WORD = CATION - 2ND WORD = ANION NAME WITH “IDE” IN THE ENDING.