Putting Atoms Together (7.1)

ELEMENTS Consist of only one kind of atom Cannot be broken down into a simpler type of matter by either physical or chemical means Can exist as either atoms (eg. helium) or molecules (eg., nitrogen). The atoms of the element helium, He The molecules of the element nitrogen, N2

Molecules Can consist of 2 or more atoms of the Same element (molecular element) (eg. N2) Different elements (molecular compound) (eg. H2O)

Diatomic Elements Diatomic elements are more stable when joined in a pair There are seven elements that form molecules consisting of two atoms. H2, N2, O2, F2, Cl2, Br2, I2 (H O Br F I N Cl)

The molecules of the compound water COMPOUNDS Consist of atoms of two or more different elements bonded together Can be broken down into a simpler type of matter (elements) by chemical means (but not by physical means) Have properties that are different from the component elements Always contain the same ratio of component atoms (constant composition). The molecules of the compound water

Element, Compound, or Mixture? Gas Liquid Solid A Element B Mixture Compound C

Element, Compound, or Mixture? Gas Liquid Solid D Compound Element E F Mixture

Chemical Formula is the notation used to indicate the type and number of atoms in a pure substance Ex) Sugar: C12H22O11 How many: carbons ____ hydrogens ____ oxygens ____ Ex) Write the chemical formula for ammonia which has one nitrogen and three hydrogens _______ 12 22 11 NH3

The OCTET RULE & IONS electrons valence 8 The octet rule is a simple chemical theory that states that atoms gain, lose, or share _____________ so that they have eight electrons in their outer_________ shells, similar to the noble gases. In simple terms, atoms are more stable when the outer shells of their atoms have _____ electrons. hydrogen & helium only need to fill the 1st energy level (2 electrons) to become stable. electrons valence 8

When an atom loses or gains electrons (in order to have 8 valence electrons), it becomes charged and is known as an ______. Atoms that gain electrons become _________ charged ions or _______. Atoms that lose electrons become _________ charged ions or ________. Ions have _____ outer shells and are ________. ion negatively anions positively cations full stable

NOBLE GASES a) Describe the chemical reactivity of the NOBLE GASES. very stable / not reactive Draw Bohr-Rutherford diagrams for He, Ne, and Ar. He Ne Ar c) Why are the NOBLE GASES stable and unreactive? 2 10 18   They all have full outer shells

ALKALI METALS  2. a) Describe the chemical reactivity of the ALKALI METALS. Very reactive b) Draw Bohr-Rutherford diagrams for Li, Na, and K. Li Na K 3 11 19

ALKALI METALS  c) Why are the ALKALI METALS reactive (why are they not stable)?   They do not have a full outer shell It is easier for the atoms of the alkali metals to ___________electrons in order to get a full outer energy level. How many electrons should the ALKALI METALS lose from their outer shell to be stable? _______ lose 1

ALKALI METALS   e) How many positive charges (protons) are there in Li+? ________ How many negative charges (electrons) are there in Li+? ________ What is the total charge on the stable Li+ ion? ________ f) How many positive charges (protons) are there in Na+? ________ How many negative charges (electrons) are there in Na+?________ What is the total charge on the stable Na+ ion? ________ g) What is the charge on ions of the ALKALI METALS? ________ 3+ 2- 1+ 11+ 10- 1+ 1+

HALOGENS 3. a) Describe the chemical reactivity of the HALOGENS. Very reactive b) Draw Bohr-Rutherford diagrams for F and Cl. F Cl 9 17

HALOGENS  c) Why are the HALOGENS reactive (why are they not stable)?   They do not have a full outer shell d) It is easier for the atoms of the halogens to ___________electrons in order to get a full outer energy level. How many electrons should the HALOGENS gain for their outer shell to be stable? _______ gain 1

HALOGENS d) How many positive charges (protons) are there in F-? ________ How many negative charges (electrons) are there in F-? ________ What is the total charge on the stable F- ion? ________ f) How many positive charges (protons) are there in Cl-? ________ How many negative charges (electrons) are there in Cl-? ________ What is the total charge on the stable Cl- ion? ________ What is the charge on ions of the HALOGENS? ________ 9+   10- 1- 17+ 18- 1- 1-

Let’s label the ionic charge trends on our Periodic Tables

Homework pg 261 #1-9