Chapter 3: Periodic Table Review {Chem}

Diatomic Elements

(7 Up!) H, N, O, F, Cl, Br, I

Which element in Group 15 has the strongest metallic character? 1. Bi 2. As 3. P 4. N

1, From left to right across the period, metallic character decreases. But it increases going down a group (last element in a group will have the most metallic character). Bi is the last element in group 15 so it is the most metallic.

The first ionization energy of an element is 736 kJ per mole of atoms. An atom of this element in the ground state has a total of how many valence electrons? 1. 1 2. 2 3. 3 4. 4

2

When combining with nonmetallic atoms, metallic atoms generally will 1. lose electrons and form negative ions 2. lose electrons and form positive ions 3. gain electrons and from negative ions 4. gain electrons and form positive ions

2, Metals tend to lose electrons and form positive ions. A neutral atom of Li has 3 protons (+) and 3 electrons (-). If it loses an electron, the Li atom now has +3 and -2 or a net charge of +1. Metals also have low electronegativities and low ionization energies.

Which three groups of the Periodic Table contain the most elements classified as metalloids (semimetals)? 1. 1, 2, and 13 2. 2, 13, and 14 3. 14, 15, and 16 4. 16, 17, and 18

3

At STP, solid carbon can exist as graphite or as diamond. These two forms of carbon have 1. the same properties and the same crystal structures 2. the same properties and different crystal structures 3. different properties and the same crystal structures 4. different properties and different crystal structures

4

When a metal atom combines with a nonmetal atom, the nonmetal atom will 1. lose electrons and decrease in size 2. lose electrons and increase in size 3. gain electrons and decrease in size 4. gain electrons and increase in size

4, Metals tend to lose electrons (becoming smaller ions) while nonmetals tend to gain electrons and become larger ions.

Solids, Liquids, Gases

All metals are in either solid or liquid phase at STP Nonmetals can be solid, liquid or gas at STP Metalloids are solid at STP

Electronegativity and Ionization Energy

As you go DOWN a GROUP, it DECREASES since more shells are added making electrons further away and harder to attract(Electronegativity) and easier to remove(Ion.) As you go ACROSS a PERIOD, it INCREASES, since the nuclear strength increases while shell amount stays the same

Atomic Radius Trend

As you go DOWN a GROUP, it INCREASES, since more shells are added and placed further and further away to fit. As you go ACROSS a PERIOD, it DECREASES since the nuclear strength increases while the shell amount stays the same

As the elements in Group 17 on the Periodic Table are considered from top to bottom, what happens to the atomic radius and the metallic character of each successive element? 1. The atomic radius and the metallic character both increase. 2. The atomic radius increases and the metallic character decreases. 3. The atomic radius decreases and the metallic character increases. 4. The atomic radius and the metallic character both decrease.

Atomic Radius increases as well as the metallic character

Which element is a liquid at STP and has low electrical conductivity? 1. silver 2. mercury 3. barium 4. bromine

Bromine

Which element in Group 1 has the greatest tendency to lose an electron? 1. cesium 2. rubidium 3. potassium 4. sodium

Cesium. (refer to reference table s in the C. R. T. and look at the first ionization energies. Cesium has the lowest.)

Which halogens are gases at STP? 1. chlorine and fluorine 2. chlorine and bromine 3. iodine and fluorine 4. iodine and bromine

Chlorine and Fluorine. Lighter substances seem to be gases

As the elements in Group 17 are considered in order of increasing atomic number, the chemical reactivity of each successive element

Decreases

Non metals

Far right on PT, often dull and brittle, good insulators, Gases and solids at STP, Low melting points, many (5-8) valence electrons, forms negative or no ions. EX: H, O, F, Ne, Kr, I, Cl

Periods

Go across in rows, all have the same number of shells of electrons (same as period number!)

Groups

Go down in columms. Have the same number of valence electrons in common Group 1: Alkali Metals Group 2: Alkaline Earth Metals Group 17: Halogens Group 18: Noble Gases Block of Groups 3-12: Transition Metals

Stability and Reactivity Part 2

Group 1 and 17 most reactive. Then 2 and 16, then group 13 and 15, and finally 14 is least reactive. Groups 3-12 are inert, or non reactive

Periodic Table is arranged by

Increasing atomic number

Metalloids

Located along bolded stairs, appearance is combo of dull and shiny, semi-conductors, solids at STP, moderate melting point, some valence electrons (3-6), Forms either positive or negative ions. EX: B, Si, Ge, As, Sb, Te

Metals

Located on left two thirds of the PT, often malleable, shiny, great conductors, State at STP is solid, High melting point, few valence electrons, forms positive ions. EX: Li, Na, Ni, Ag, Fe, Al

The least reactive elements of the periodic table are

Noble Gases

Stability & Reactivity

The goal of an atom is to have a full valence shell. This is called the Octet Rule (Get to 8) doesn't apply to H and He because shell #1 is maxed out at 2 electrons! Reacting basically involves gaining or losing valence electrons. Gain e if you need more and become a negative ion, Lose e if you need less and become a positive ion.

Which element has properties most like those of magnesium? 1. calcium 2. cesium 3. potassium 4. sodium

calcium, properties are alike in the same group of the periodic table

Electronegativity and Ionization Energy also

increase going from bottom left (Fr) to top right (F)

Atomic Radius also

increases going from top right (F) to bottom (Fr)

Dmitri Mendeleev

main scientist recognized for contributing to the Periodic Table

Chemical Properties ( Like Stability and Reactivity) are based on

number of valence electrons