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 • Atoms are comprised of:

– Protons –Neutrons – Electrons

– Protons • Positively charged subatomic particles • ALL protons located within the atom’s nucleus

– Electrons • Negatively charged subatomic particles • All electrons are located ‘outside’ of the atom in its ORBITALS

– Neutrons • Have NO CHARGE • Located INSIDE the nucleus along w/ the protons

The periodic table

• Each element is located in

–A vertical column called a GROUP

–A 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

–Hydrogen is not an alkali metal – As with all families, these elements share traits.

• They are very reactive. • Why? • They all have one electrons in their outer shell

• Group 1 contains: ‒ Lithium (Li) ‒ Sodium (Na) ‒ Potassium (K) ‒ Rubidium (Rb) ‒ Cesium (Cs) ‒ Francium (Fr)

GROUP 2 = ALKALINE EARTH METALS

• The second most reactive group of elements.

• They are called alkaline b/c when these compounds are mixed in solutions:

– Likely to form solutions with a pH greater than 7. • A high pH solution is defined as a "basic" or "alkaline"

solution.

GROUP 2 = ALKALINE EARTH METALS

• Group 2 contains: ‒ Beryllium (Be) ‒ Magnesium (Mg) ‒ Calcium (Ca) ‒ Strontium (Sr) ‒ Barium (Ba) ‒ Radium (Ra)

– Each has two electrons in their outer shell.

– Likely to give up those two electrons in electrovalent/ionic bonds.

GROUPS 3-12 = TRANSITION METALS

Groups 3-12 contain: • 21 (Scandium) through 29 (Copper) • 39 (Yttrium) through 47 (Silver) • 57 (Lanthanum) through 79 (Gold) • 89 (Actinium) and all higher numbers

GROUPS 3-12 = TRANSITION METALS

• Transition metals are good examples of advanced shell and orbital ideas.

• They have a lot of electrons and distribute them in different ways.

• Transition metals are usually shiny. – E.g. silver (Ag), gold (Au), and platinum (Pt)

• Most elements can only use electrons from their outer orbital to bond with other elements.

• Transition metals can use the two outermost shells/orbitals to bond with other elements.

GROUP 17 = HALOGENS • The halogens have seven electrons in their outer

shell.

• Instead of this making them more stable, they are actually VERY reactive ‒ Can anyone guess why?

‒ Are we there yet, syndrome…

‒ Often will form bonds with metals and elements from Group 1.

• Group 17 contains: ‒ Fluorine (F) ‒ Chlorine (Cl) ‒ Bromine (Br) ‒ Iodine (I) ‒ Astatine (At)

GROUP 18 = NOBLE GASES • Also known as GROUP ZERO

• The happiest of elements

– Have 8 electrons in their outer M electron shell.

• Non-reactive, but still used industrially & daily – Neon lights (Las Vegas, your local nail shop) – Used in industrially to stabilize reactions which would

otherwise proceed too quickly

• Group 18 contains: – Helium (He) – Neon (Ne) – Argon (Ar) – Krypton (Kr) – Xenon (Xe) – Radon (Rn)

Lewis dot structures: Valence Electrons

• Valence Electrons:

–Outer shell electrons

–Electrons in the highest occupied energy level of the atom

–The only electrons involved in bond formation (for most elements).

• Shared or given/taken away.

Lewis Dot: Bohr Atomic Structures

• The first energy level can contain two electrons

• The second and third levels can contain 8 electrons

• Beyond the third level, energy levels can contain 18 or up to 32 electrons

Lewis Dot Structures: What are they?

• What are Lewis Dot Structures?

– Also known as electron dot structure or Lewis dot diagrams

– A notation showing the valence (outer shell) electrons surrounding an atom.

Lewis Dot Structures: How To

• Figure out which group (column) the element of interest lives in.

• This will tell you the number of valence electrons of the element.

• For these diagrams you draw ONLY the VALENCE electrons

Lewis Dot Structures: How To

• Write the symbol for the element.

• Nitrogen is in group 5A, so it has 5 valence electrons.

• 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 • Not all shells hold the same number of

electrons.

• For the first eighteen elements, there are some easy rules: – The K shell only holds two electrons.

– The L shell only holds eight electrons.

– The M shell only holds eight electrons. • The M shell can actually hold up to 18 electrons as you move to higher

atomic numbers.

– The maximum number of electrons you will find in any shell is 32.

• For our purposes, we’re only going to focus on the elements having an M SHELL (it is happiest with 8 electrons).

ORBITALS • Electrons are always moving.

• They orbit very rapidly around an atom’s nucleus.

• Each electron has a ‘shell’ , or orbit in which it must remain. – Electrons in the first shell are closer to the nucleus

– Electrons in the outer shell are the furthest away from the nucleus

– The further an electron is from the nucleus the more likely that it is not: • As stabilized by the positive charge of the nucleus (as are electrons

closer to the nucleus)

• And therefore, electrons in the outer shells are usually ‘not happy.’

ELEMENTS & IONS

• A neutral atom has:

–Equal numbers of protons and electrons

–A neutral atom is termed an ELEMENT

• An element becomes charged when:

–The number of its protons and electrons becomes different

–A charged atom is termed an ION

ELEMENTS & IONS

𝑵𝒂 →

• The Na atom:

–Lost an electron

–Became Positively charged

–Is now a CATION

• A cation is a POSITIVELY charged ion.

𝑵𝒂+

ELEMENTS & IONS

𝑪𝒍 →

• The Cl atom: –Gained an electron

–Became Negatively charged

– Is now an ANION • An anion is a NEGATIVELY charged ion.

• I remember it by: A Negative ion = ANION

𝑪𝒍-

ATOMIC NUMBER, ATOMIC WEIGHT &

MASS NUMBER • The atomic number (Z):

– Equals the number of protons in an atom

– The number of protons is what distinguishes one element from another

– All atoms of a given element have the SAME NUMBER of protons

• The mass number (A): – Equals the number of protons &

neutrons in an atom.

ATOMIC NUMBER, ATOMIC WEIGHT &

MASS NUMBER

• The atomic weight (or atomic mass):

‒ How much one atom of an element weighs

‒ Measured either in amu or g/mol

Determining Molar Mass

𝑚𝑎𝑠𝑠 𝑜𝑓 1 𝑚𝑜𝑙 𝐶 = 12.011 𝑔 𝑚𝑎𝑠𝑠 𝑜𝑓 1 𝑚𝑜𝑙 𝐻 = + 1.008 𝑔

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).

× 𝟒 𝑚𝑎𝑠𝑠 𝑜𝑓 1 𝑚𝑜𝑙 𝐶𝐻4 = 16.04g

Determining Molar Mass

𝑚𝑎𝑠𝑠 𝑜𝑓 1 𝑚𝑜𝑙 𝐶 = 12.011 𝑔 𝑚𝑎𝑠𝑠 𝑜𝑓 1 𝑚𝑜𝑙 𝐻 = + 1.008 𝑔

× 𝟒

𝑚𝑎𝑠𝑠 𝑜𝑓 1 𝑚𝑜𝑙 𝐶𝐻4 = 16.04g

Now convert the molar mass of methane to molecules of methane. Hint: Use Avogadro’s number Hint #2: 1 mol = 6.022*1023 molecules

𝟏 𝒎𝒐𝒍 𝑪𝑯𝟒

𝟏𝟔. 𝟎𝟒 𝒈×

𝟔. 𝟎𝟐𝟐 ∗ 𝟏𝟎𝟐𝟑𝒂𝒕𝒐𝒎𝒔 𝒐𝒇 𝑪𝑯𝟒

𝟏 𝒎𝒐𝒍=

Chemical Equations • What is a “chemical equation”?

– “A 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.

– The coefficients next to the symbols and formulas of [atomic] entities are the absolute values of the stoichiometric numbers.”*

𝑨 + 𝑩 → 𝑪 + 𝑫 (REACTANTS) (PRODUCTS)

2HCl + 2Na → 2NaCl + H2

coefficients subscript

CHEMICAL REACTIONS

• Precipitation Reaction

– A reaction wherein the mixture of two solutions form a solid which separates out of the solution

• Acid-Base Reaction

– A reaction wherein acids or bases interact and exchange either Hydrogen atoms or electrons

• Oxidation-Reduction reaction

– A reaction involving the exchange of electrons between reactants

LAW OF CONSERVATION • Through countless experiments conducted in the

1700s, scientists were able to make a number of discoveries in the field of chemistry.

• One such discovery involves the weighing of reactants and products of chemical reactions.

• This led to the idea that mass is neither created nor destroyed, but that it is conserved.

• This is called the Law of Conservation of Mass

• The same concept can be applied to energy.