Chemistry Review Do you remember anything from science investigations?

Atomic Structure Nucleus- center of an atom -contains protons - which are positive -contains neutrons- which are neutral Electrons (which are negative) surround the nucleus in energy levels 1 st energy level = holds 2e 2 nd energy level = holds 8e 3 rd energy level = holds 18e 4 th energy level = holds 32e

Bohr Model of Atom

Periodic Table tidbits Period table organization – organized by increasing atomic number Split into metals (left side of stair step line) and nonmetals (right side of stair step line) Groups – vertical columns (#1-18) Periods – horizontal rows (#1-7)

More Chemistry tidbits Atomic number = number of protons Mass number = # protons + # neutrons #Neutrons = mass number - # protons # protons = # electrons REMEMBER “APE”= ATOMIC NUMBER, #PROTONS, #ELECTRONS WILL EQUAL EACH OTHER IN A NEUTRAL ATOM

Isotopes (I said isotope you dope!) Isotopes are different atoms of the same element that contain the same number of protons but different number of neutrons. Examples Cl-35 vs. Cl-37 17P 17P 18N 20N

Chemical Bonding Remember atoms bond with one another in order to become stable (need to get 8 electrons in outer ring) Exception- hydrogen only needs 2 electrons in outer ring to be stable Bonds are forces of attraction between elements Involves bonding of valence electrons (electrons in outermost shell)

Lewis Dot Structures Lewis dot diagrams- display the number of valence electrons (outermost electrons) around the element symbol Used to show how atoms of different elements bond and form compounds Hint- use group number to find valence electrons

Electron configurations

Lewis Dot Diagrams

Types of Bonds Covalent bond – sharing of electrons -occurs between 2 nonmetals -types- single (shares 1 e) double (shares 2 e) triple (shares 3 e) *REMEMBER HYDROGEN IS A NONMETAL AND FORMS COVALENT BONDS!!!

Covalent bonds H 2 -hydrogen gas-sharing of electrons

Types of Bonds Ionic bond- one atom gives an electron to another atom (remember it’s the losing and gaining of electrons) Involves forming ions (have positive and negative charges) Occurs between a metal and a nonmetal

Bond Diagrams Covalent bonds-remember they share electrons Ex. F 2

Bond Diagrams Ionic Bond- -lose & gain electrons Ex. NaCl

Ionic bond Lewis dot diagram NaCl- sodium chloride

Covalent Bond Lewis dot structure HF-hydrogen fluoride

What is inside the nucleus of an atom? 1. Protons and electrons 2. Electrons and neutrons 3. Protons only 4. Protons and neutrons

What are the dots in Lewis dot diagrams? 1. Number of protons 2. Number of neutrons 3. Number of valence electrons 4. Number of inner shell electrons

An ionic bond is between 1. 1 metal and 1 nonmetal 2. 2 nonmetals 3. 2 metals 4. None of the above

A covalent bond is between 1. 2 metals 2. 1 metal and 1 nonmetal 3. 2 nonmetals 4. 3 metals

How do you find the number of valence electrons to draw for a Lewis dot diagram 1. Look at the atomic number 2. Look at the mass number 3. Look at the number of neutrons 4. Look at the group number