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TEST REVIEW: PERIODIC TABLE 1. Know the subatomic particles and their charges. 2. Know how to read a periodic table (rows, periods, electronegativity) and
apply that information to chemical equations. 3. Be able to compare and contrast the different groups of the periodic
table. 4. Know how to write the Lewis Dot Structures for groups 1-2, & 3A-
8A(remember group 3A = group 13 and cetera). 5. Know how valence electrons and orbitals relate. 6. Know what orbitals are. 7. Know and understand elements and ions. 8. Know how to break a compound down into its ionic components using
Lewis dot structures and valence electrons. 9. Be able to compare and contrast, atomic number, atomic weight and
mass number. 10. Be able to find molar mass (using the CORRECT set-up; as shown in
class). 11. Be able to compare and contrast different chemical reactions. 12. Be able to apply the Law of Conservation of Mass.
The periodic table โข Atoms are comprised of:
โ Protons โNeutrons โ Electrons
โ Protons โข Positively charged subatomic particles โข ALL protons located within the atomโs nucleus
โ Electrons โข Negatively charged subatomic particles โข All electrons are located โoutsideโ of the atom in its ORBITALS
โ Neutrons โข Have NO CHARGE โข Located INSIDE the nucleus along w/ the protons
The periodic table
โข Each element is located in
โA vertical column called a GROUP
โA horizontal row called a PERIOD
The periodic table
A vertical column is called a GROUP
The periodic table
A horizontal row is called a PERIOD
GROUP 1 = ALKALI METALS
โHydrogen is not an alkali metal โ As with all families, these elements share traits.
โข They are very reactive. โข Why? โข They all have one electrons in their outer shell
โข Group 1 contains: โ Lithium (Li) โ Sodium (Na) โ Potassium (K) โ Rubidium (Rb) โ Cesium (Cs) โ Francium (Fr)
GROUP 2 = ALKALINE EARTH METALS
โข The second most reactive group of elements.
โข They are called alkaline b/c when these compounds are mixed in solutions:
โ Likely to form solutions with a pH greater than 7. โข A high pH solution is defined as a "basic" or "alkaline"
solution.
GROUP 2 = ALKALINE EARTH METALS
โข Group 2 contains: โ Beryllium (Be) โ Magnesium (Mg) โ Calcium (Ca) โ Strontium (Sr) โ Barium (Ba) โ Radium (Ra)
โ Each has two electrons in their outer shell.
โ Likely to give up those two electrons in electrovalent/ionic bonds.
GROUPS 3-12 = TRANSITION METALS
Groups 3-12 contain: โข 21 (Scandium) through 29 (Copper) โข 39 (Yttrium) through 47 (Silver) โข 57 (Lanthanum) through 79 (Gold) โข 89 (Actinium) and all higher numbers
GROUPS 3-12 = TRANSITION METALS
โข Transition metals are good examples of advanced shell and orbital ideas.
โข They have a lot of electrons and distribute them in different ways.
โข Transition metals are usually shiny. โ E.g. silver (Ag), gold (Au), and platinum (Pt)
โข Most elements can only use electrons from their outer orbital to bond with other elements.
โข Transition metals can use the two outermost shells/orbitals to bond with other elements.
GROUP 17 = HALOGENS โข The halogens have seven electrons in their outer
shell.
โข Instead of this making them more stable, they are actually VERY reactive โ Can anyone guess why?
โ Are we there yet, syndromeโฆ
โ Often will form bonds with metals and elements from Group 1.
โข Group 17 contains: โ Fluorine (F) โ Chlorine (Cl) โ Bromine (Br) โ Iodine (I) โ Astatine (At)
GROUP 18 = NOBLE GASES โข Also known as GROUP ZERO
โข The happiest of elements
โ Have 8 electrons in their outer M electron shell.
โข Non-reactive, but still used industrially & daily โ Neon lights (Las Vegas, your local nail shop) โ Used in industrially to stabilize reactions which would
otherwise proceed too quickly
โข Group 18 contains: โ Helium (He) โ Neon (Ne) โ Argon (Ar) โ Krypton (Kr) โ Xenon (Xe) โ Radon (Rn)
Lewis dot structures: Valence Electrons
โข Valence Electrons:
โOuter shell electrons
โElectrons in the highest occupied energy level of the atom
โThe only electrons involved in bond formation (for most elements).
โข Shared or given/taken away.
Lewis Dot: Bohr Atomic Structures
โข The first energy level can contain two electrons
โข The second and third levels can contain 8 electrons
โข Beyond the third level, energy levels can contain 18 or up to 32 electrons
Lewis Dot Structures: What are they?
โข What are Lewis Dot Structures?
โ Also known as electron dot structure or Lewis dot diagrams
โ A notation showing the valence (outer shell) electrons surrounding an atom.
Lewis Dot Structures: How To
โข Figure out which group (column) the element of interest lives in.
โข This will tell you the number of valence electrons of the element.
โข For these diagrams you draw ONLY the VALENCE electrons
Lewis Dot Structures: How To
โข Write the symbol for the element.
โข Nitrogen is in group 5A, so it has 5 valence electrons.
โข Starting at the right, draw the 5 electrons clockwise around the element symbol
N
Lewis Dot Structures Elements within the same group have the same
electron-dot diagrams. REMEMBER THESE DIAGRAMS ARE INCORRECT BUT THE # OF ELECTRONS IS CORRECT!
Remember: Electronegativity trend Electronegativity is a measure of the tendency of an atom to attract
(or take) a bonding pair of electrons.
ORBITALS
ORBITALS โข Not all shells hold the same number of
electrons.
โข For the first eighteen elements, there are some easy rules: โ The K shell only holds two electrons.
โ The L shell only holds eight electrons.
โ The M shell only holds eight electrons. โข The M shell can actually hold up to 18 electrons as you move to higher
atomic numbers.
โ The maximum number of electrons you will find in any shell is 32.
โข For our purposes, weโre only going to focus on the elements having an M SHELL (it is happiest with 8 electrons).
ORBITALS โข Electrons are always moving.
โข They orbit very rapidly around an atomโs nucleus.
โข Each electron has a โshellโ , or orbit in which it must remain. โ Electrons in the first shell are closer to the nucleus
โ Electrons in the outer shell are the furthest away from the nucleus
โ The further an electron is from the nucleus the more likely that it is not: โข As stabilized by the positive charge of the nucleus (as are electrons
closer to the nucleus)
โข And therefore, electrons in the outer shells are usually โnot happy.โ
ELEMENTS & IONS
โข A neutral atom has:
โEqual numbers of protons and electrons
โA neutral atom is termed an ELEMENT
โข An element becomes charged when:
โThe number of its protons and electrons becomes different
โA charged atom is termed an ION
ELEMENTS & IONS
๐ต๐ โ
โข The Na atom:
โLost an electron
โBecame Positively charged
โIs now a CATION
โข A cation is a POSITIVELY charged ion.
๐ต๐+
ELEMENTS & IONS
๐ช๐ โ
โข The Cl atom: โGained an electron
โBecame Negatively charged
โ Is now an ANION โข An anion is a NEGATIVELY charged ion.
โข I remember it by: A Negative ion = ANION
๐ช๐-
ATOMIC NUMBER, ATOMIC WEIGHT &
MASS NUMBER โข The atomic number (Z):
โ Equals the number of protons in an atom
โ The number of protons is what distinguishes one element from another
โ All atoms of a given element have the SAME NUMBER of protons
โข The mass number (A): โ Equals the number of protons &
neutrons in an atom.
ATOMIC NUMBER, ATOMIC WEIGHT &
MASS NUMBER
โข The atomic weight (or atomic mass):
โ How much one atom of an element weighs
โ Measured either in amu or g/mol
Determining Molar Mass
๐๐๐ ๐ ๐๐ 1 ๐๐๐ ๐ถ = 12.011 ๐ ๐๐๐ ๐ ๐๐ 1 ๐๐๐ ๐ป = + 1.008 ๐
Each mole of methane contains ONE mole of carbon atoms and FOUR moles of hydrogen
This is referred to as the molar mass of methane (CH4).
ร ๐ ๐๐๐ ๐ ๐๐ 1 ๐๐๐ ๐ถ๐ป4 = 16.04g
Determining Molar Mass
๐๐๐ ๐ ๐๐ 1 ๐๐๐ ๐ถ = 12.011 ๐ ๐๐๐ ๐ ๐๐ 1 ๐๐๐ ๐ป = + 1.008 ๐
ร ๐
๐๐๐ ๐ ๐๐ 1 ๐๐๐ ๐ถ๐ป4 = 16.04g
Now convert the molar mass of methane to molecules of methane. Hint: Use Avogadroโs number Hint #2: 1 mol = 6.022*1023 molecules
๐ ๐๐๐ ๐ช๐ฏ๐
๐๐. ๐๐ ๐ร
๐. ๐๐๐ โ ๐๐๐๐๐๐๐๐๐ ๐๐ ๐ช๐ฏ๐
๐ ๐๐๐=
Chemical Equations โข What is a โchemical equationโ?
โ โA chemical equation is the symbolic representation of a chemical reaction wherein the [reactants] are given on the left hand side and the [products] on the right hand side.
โ The coefficients next to the symbols and formulas of [atomic] entities are the absolute values of the stoichiometric numbers.โ*
๐จ + ๐ฉ โ ๐ช + ๐ซ (REACTANTS) (PRODUCTS)
2HCl + 2Na โ 2NaCl + H2
coefficients subscript
CHEMICAL REACTIONS
โข Precipitation Reaction
โ A reaction wherein the mixture of two solutions form a solid which separates out of the solution
โข Acid-Base Reaction
โ A reaction wherein acids or bases interact and exchange either Hydrogen atoms or electrons
โข Oxidation-Reduction reaction
โ A reaction involving the exchange of electrons between reactants
LAW OF CONSERVATION โข Through countless experiments conducted in the
1700s, scientists were able to make a number of discoveries in the field of chemistry.
โข One such discovery involves the weighing of reactants and products of chemical reactions.
โข This led to the idea that mass is neither created nor destroyed, but that it is conserved.
โข This is called the Law of Conservation of Mass
โข The same concept can be applied to energy.