Atomic Structure PDF

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.