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Mr. Nelson Chemistry. The Periodic Table. Periodic Table. Group – Vertical columns on PT Period – Horizontal rows on PT. Main-Group Elements. Groups 1 , 2 , and 13-18. Main-Group Elements.
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Mr. Nelson Chemistry The Periodic Table
Periodic Table • Group – Vertical columns on PT • Period – Horizontal rows on PT
Main-Group Elements • Groups 1, 2, and 13-18
Main-Group Elements • The chemical properties of the main-group elements depends on their number of valence electrons • Valence electrons are the outermost electrons involved in chemical bonding
Valence Electrons & Chemical Properties • Each group of the main-group elements has the same number of valence electrons • Each element wants to be as stable as possible • All main-group elements want a full shell of electrons, which is 8 valence electrons
Valence Electrons & Chemical Properties • Each group forms ions based on the easiest way to obtain this full shell • Also known as the octet rule
Family Groups • Noble Gases (Group 18) • Examples: Ne, Xe • Description: stable, unreactive group of gases • Number of Valence Electrons: 8 • Forms NO ions
Family Groups • Halogens (Group 17) • Examples: F, Cl • Description: Highly reactive group of gases • Number of Valence Electrons: 7 • Forms 1- ions
Family Groups • Alkali Metals (Group 1) • Examples: Na, K (not H) • Description: Highly reactive group of metals • Number of Valence Electrons: 1 • Forms 1+ ions
Family Groups • Alkaline-Earth Metals (Group 2) • Examples: Be, Mg • Description: Slightly less reactive group than alkali metals • Number of Valence Electrons: 2 • Forms 2+ ions
Family Groups • Transition Metals (Group 3 – 12) • Examples: Fe, Au, Ag • Description: Fairly stable group of metals • Forms multiple ions
Family Groups • Lanthanides & Actinides • Location: Bottom 2 periods of PT • Description: Heavy metals, synthetics, radioactive
States of Matter • Metals and Nonmetals (Staircase)
Periodic Table Trends • Atomic Size • Definition: The volume occupied by the electrons around a nucleus • Period Trend • Caused by: Increasing Effective Nuclear Charge
Atomic Size • Effective nuclear charge is the amount of charge felt by outer electrons in an atom • Group trend • Caused by: Increasing electron energy levels
Ionization Energy • Definition: The amount of energy required to remove one electron • Period trend • Caused by: Inc. Effective Nuclear Charge
Ionization Energy • Group trend • Caused by: Electron shielding • Electron shielding occurs when inner electrons shield outer electrons from the pull of the nucleus
Electron Affinity • Definition: The attraction of an atom for an electron • Period Trend • Caused by: Inc. Eff. Nuclear Charge
Electron Affinity • Group trend • Caused by: Inc. electron shielding
Electronegativity • Definition: How much an atom in a chemical bond attracts electrons • Period trend • Caused by: Inc. Eff. Nuclear Charge
Electronegativity • Group trend • Caused by: Electron shielding/Inc. electron energy levels
Filling Electron Orbitals • Orbitals are the area in space where electrons are found • Each individual orbital holds 2 electrons • There are four main shapes which hold a different number of electrons
Shapes of Orbitals • The four shapes are s, p, d, and f
Shapes of the Orbitals • Each shape holds a different number of orbitals • s has 1 orbital, p has 3 orbitals, and d has 5 orbitals • www.ptable.com
Energy Levels • Each period is a new energy level • Like an elevator, electrons cannot exist between energy levels!
General Rules • Aufbau Principle – Electrons fill lowest energy level first • Analogy: Lazy Tenant Rule
General Rules • Pauli Exclusion Principle – Electrons must have opposite spin (up/down) when in the same orbital • Analogy: Yin and Yang Rule
General Rules • Hund’s Rule – Electrons in equal energy orbits fill orbitals with parallel spin • Analogy: Empty Bus Seat Rule
Orbital Notation • Specific order for filling electrons – based on periodic table • Examples • Beryllium • Oxygen
Orbital Notation • Examples • O2- • Titanium
Electron Configuration • Examples • Silicon • Selenium • Manganese
Shorthand Electron Config • Shorter version of writing electron configurations • Noble Gas Core – inner core of electrons not involved in chemical bonding