Warm up An element is dull, silvery in color, can be cut with a knife and is very reactive in water. What family could this be in?

Properties of Atoms and the Periodic Table

Structure of the Atom

Atomic Compounds Atom—smallest piece of matter that still retains the property of the element Element of silver=only atoms of silver Element of hydrogen=only atoms of hydrogen Atoms are composed of sub-atomic particles called protons, electrons, and neutrons.

Electron Cloud Model- current model Electrons don’t follow fixed orbits Area around the nucleus where electrons are most likely found

Electron Cloud Model Electron Cloud—area around the nucleus of an atom where its electrons are most likely found Energy level-areas of the cloud where the electrons are more likely to be found

Energy Levels Electron Cloud: electrons orbit the nucleus in patterns, rings Closer to the nucleus= low energy Further from the nucleus= high energy

Energy Levels Each energy level has a maximum number of electrons it can hold: Energy Level Maximum Electrons 1 2 8 3 18 4 32

Octet Rule In the 1st three energy levels the electrons will not begin to fill the next energy level until the previous one is full Octet Rule: 8 electrons makes an energy level full and stable Less than 8 is unstable Electrons will try to bond with other elements so they have 8 electrons in their outer level.

Valence Electrons Valence Electrons are the electrons in the last shell or energy level of an atom Show a repeating pattern across the periodic table Valence electrons increase in number as you go across a period on the periodic table

Valence Electrons Are located furthest from the nucleus (have the most energy) Electrons responsible for the bonding of elements to form compounds

Visualizing Electrons in Atoms Two ways to diagram electrons and bonding in atoms: Bohr Diagrams Lewis Dot Structures/Electron Dot Diagram H Cl Dots represent Electrons

Bohr Diagrams Bohr Diagrams are a way to represent the number of electrons in an element In Bohr Diagrams the number of electrons are represented in orbits around the nucleus (protons and neutrons)

Lewis Dot/Electron Dot Lewis dot structures represent the number of electrons in the outer energy level The number of valence electrons for each element must be known to construct the structures

Lewis Dot/Electron Dot You can use Lewis Dot structures to visualize how bonds are made between elements forming compounds The valence electrons are the electrons that are gained, lost, or shared

Ne To construct Lewis Dot Structures: Identify the valence electrons Construct the Bohr diagram if you do not know the # of valence electrons Write the chemical symbol Use dots to represent the valence electrons; place the electrons around the symbol in the order to the right 1 5 Ne 8 2 4 6 7 3

Organizing the Elements Periodic means “repeated in a pattern” Dmitri Mendeleev (1869): arranged the elements in order by increasing atomic masses

Organizing the Elements Periodic Table: the elements are arranged by increasing atomic masses and by changes in physical and chemical properties

Groups/Families Vertical columns (1-18) Represents the number of valence electrons Atoms have similar properties Atoms become more reactive as you move down a column

The Group numbers on top and form columns for “groups” or “families” 1 18 2 13 14 15 16 17 3 4 5 6 7 8 9 10 11 12 This is group 1 the alkali group. Families have similar but not identical characteristics

Periods Horizontal rows on the periodic table Represent the # of energy levels

Periods run down the side and form rows of “periods” 1 2 3 4 This is period number 3 Which means it has 3 energy levels 5 6 7

Periods Represent the Number of outer rings Or what scientists call “energy Levels” of electrons Energy Level 1: H & He Locate them on your periodic table electron

Periods Represent the Number of outer rings Or what scientists call “energy Levels” Energy Level 2: Li, Be, B, C, N, O, F & Ne Locate them on your periodic table

Periods Represent the Number of outer rings Or what scientists call “energy Levels” of electrons Energy Level 3: Na, Mg, Al, Si, P, S Cl & Ar Locate them on your periodic table

Atomic Size As you move across the table (period), the atoms size generally gets smaller As you move down the table (group), the atoms radius generally gets bigger

Metals increase in reactivity Fr Increase in reactivity

Metals Malleable—can be hammered into sheets Ductile—can be drawn into wires Shiny High melting/boiling points Good conductors of heat and electricity Radium-Boiling point is 1140 C

Nonmetals

Nonmetals Dull, brittle, powdery Low melting/boiling points Carbon Dull, brittle, powdery Low melting/boiling points Poor conductors of heat and electricity Can be solid, liquid, or gas Sulfur Chlorine Bromine

Metalloids

Metalloids Have properties of both metals and nonmetals Semi-metals Antimony Boron

Alkali Metals

Alkali Metals Group 1 Valence electron: 1 Highly reactive solids Only found as compounds Ex: sodium (Na)—found in soap and drain cleaners

Hydrogen “Special Element” Valence Electron: 1 Has properties of alkali metals …..but it is a NON-METAL

Alkaline Earth Metals

Alkaline Earth Metals Group 2 Valence electrons: 2 Highly reactive Not found free in nature Combine easily with nonmetals to form salts

Transition Metals

Transition Metals Group 3-12 Valence electrons: vary Properties vary

Halogens

Halogens Group 17 Valence electrons: 7 Called “salt formers”—combine easily with groups 1 & 2 Only group to have all 3 states of matter (solid, liquid, gas) Chlorine Gas

Noble Gases

Noble Gases Group 18 Valence electrons: 8 Very stable (electrons are in low energy states) Have everything they need “Noble” Very unlikely to bond with any other elements Inactive gases

Lanthanide Series Actinide Series

Lanthanide/Actinide Synthetic Elements Man-made elements Can be found in smoke detectors