Periodic Table

Elements What is an element? Substance that cannot be broken down into simpler substance Atom – smallest unit of matter that has the properties of an element Elements are composed of atoms that have a specific number of protons

Organizing the elements In the 1800’s, chemist Dimitri Mendeleev wanted to organize the known elements by their properties

Mendeleev Organized the elements by increasing mass All the elements in a column have similar properties He left holes in the table for elements that had yet to be discovered

Modern Periodic Table

Modern Periodic Table Element Squares Element Name Atomic Number number of protons Chemical Symbol Represents the element One or two letters Not always the same letters as in the element name Average Atomic Mass Mass of an atom of the element Average of all known isotopes on Earth Grams/mole

Modern Periodic Table Organization Metals Good conductors Malleable Mostly all solid Nonmetals Poor conductors Brittle Many are gases Metalloids Have properties of both metals and nonmetals

Modern Periodic Table States of matter

Modern Periodic Table Organization Period – row across the table Atomic number increases left to right Period Number = number of orbitals in the atom

Drawing atoms Bohr Model Draw a small circle in the middle Number of protons Number of neutrons Draw a ring around the circle for each orbital Add electrons starting closest to the center (first orbital) First orbital holds 2 electrons Second orbital holds 8 electrons Third orbital holds 8 electrons

Bohr model atom What can we learn about an atom from these drawings? Number of Protons Number of Neutrons Mass number # of protons + # of neutrons Number of electrons Number of valence electrons Charge of the atom Charge of protons + charge of electrons Ion or not

Bohr model atoms practice Draw the following atoms, name the element, and determine the charge and mass 5 protons, 4 electrons, 4 neutrons 7 protons, 10 electrons, 7 neutrons

Bohr model atoms practice Draw the following atoms and determine the number of protons and electrons Sodium, neutral charge, one more proton than neutron Nitrogen, -3 charge, #protons=#neutrons

Modern Periodic Table Organization Family/Group columns up and down

Properties Related to Groups These Properties do not apply to the middle section Oxidation Number Reactivity Valence Electrons

Properties Related to Groups Oxidation Number The number of electrons an atom is willing to gain or lose Plus = more likely to lose an electron Minus = more likely to gain an electron Oxidation number: +1 +2 +3 4 -3 -2 -1 0

Properties Related to Groups Reactivity How likely an atom is to react with another atom Groups 1 and 17 - most reactive Group 4 – least reactive Group 18 - not reactive at all

Reactivity of Elements Alkali metals https://www.youtube.com/watch?v=HvVUtpdK7xw&t=15s Halogens https://www.youtube.com/watch?v=saLvwX3_p1s

Properties Related to Groups Valence Electrons electrons found in the outermost orbital Group 1: 1 VE Group 2: 2 VE Group 13: 3 VE Group 14: 4 VE Group 15: 5 VE Group 16: 6 VE Group 17: 7 VE Group 18: 8 VE Valence Electrons: 1 2 3 4 5 6 7 8

Drawing Atoms Lewis Dot Structure Write the chemical symbol Draw valence electrons around the symbol Drawing electrons: Draw one dot on each side of the symbol if ≤ 4 valence electrons Pair electrons if 5-8 valence electrons Exception: Helium

Lewis Dot Structure What can we learn about an atom from these drawings Element name Valence electrons Practice Worksheet

Naming Families Group 1: Alkali Metals Group 2: Alkaline Earth Metals Groups 3-12: Transition Metals Group 13: Boron Family Group 14: Carbon Family Group 15: Nitrogen Family Group 16: Oxygen Family Group 17: Halogens Group 18: Noble Gases Lanthanide Series Actinide Series