Unit 4 :Periodic Table

nonmetals

(elements that appear dull, poor conductors of heat and electricity)

metals

(elements that are shiny, malleable, good conductors of heat and electricity)

metalloids

(elements that conduct heat and electricity moderately well, and possess some properties of metals and some properties of nonmetals).

Alkali metals tend to form ions with what charge?

+1

Halogens tend to form ions with what charge?

-1

Groups ________ and _______contain elements whose valence electrons are only found in the s block?

1, 2

What are the most reactive metals on the periodic table?

Alkali metals

2. Where is each group located on the periodic table?

Alkali metals: Group 1 Alkaline earth metal:; Group 2 Transition metals: Groups 3-12 Halogens: Group 17 Noble gases: Group 18

1. What are the major physical and chemical properties of each group?

Alkali metals: soft, gray, one valence electron, highly chemically reactive. Alkaline earth metals: harder than group 1, gray, more luster, two valence electrons, reactive but not as much as group 1. Transition metals: "typical" metals; shiny, hard, good conductors of heat and electricity, varying chemical reactivity. Halogens: brightly colored nonmetals, most are gaseous at room temperature, seven valence electrons, highly chemically reactive. Noble gases: colorless, odorless gas, full octet, chemically unreactive.

____________ have low ionization energies because ____________.

Alkali metals; they have the weakest effective nuclear charge in a period.

The radius of the atom increases as you move from top to bottom down a group. Why?

As the distance between the nucleus and the valence electrons increases, the force of attraction decreases making the radius larger.

The radius of the atom decreases as you move from left to right across a period. Why?

As the number of protons increases, the force of attraction between the nucleus and the electrons increases, pulling the electrons in closer to the nucleus.

Consider the valence electrons of Li, Be, B, C, N, O, F, Ne. What will happen to the force of attraction the valence electrons will feel from the nucleus as you move across the period of elements from left to right?

As you move across a period from left to right, the valence electrons will feel a stronger force of attraction due to the increased number of protons in the nucleus.

Consider the valence electrons of Li, K, Na, Rb: What will happen to the force of attraction the valence electrons will feel from the nucleus as you move down the group of elements?

As you move down the group, the valence electrons will get farther from the nucleus, so the force will get weaker.

Mendeleev organized elements in the Periodic Table by _______________________ while Mosley used ___________________________.

Atomic mass, atomic number

Why does electron shielding have very little effect on the size of the radius as you move across a period?

Because across a period, electrons are in the same shell so they experience very little shielding.

Why are noble gases unreactive?

Because they have a full valence shell of electrons.

What is effective nuclear charge?

Effective nuclear charge is the force of attraction the electrons feel from the protons in the nucleus. You examined this in the first activity in this unit.

The modern Periodic Table has elements arranged in order of increasing atomic mass.True or false?

False: Mendeleev organized the original table by mass but Moseley rearranged the elements by increasing atomic number which allowed all elements to obey the periodic law.

Henry Mosley

Fixed Mendeleevs original periodic table, oncluded that the number of protons increased by one for every consecutive element on the Periodic Table.

Nonmetals tend to _________ electrons and form _______ ions.

Gain, negative

Why did Mendeleev leave blank spaces in his Periodic Table?

He predicted the existence of elements with properties similar to that of Al and Si based on the patterns he established.

Who is responsible for the modern version of the Periodic Table? What major changes did he make?

Henry Moseley. He arranged elements by increasing atomic number instead of by mass.

which type of ions, cations or anions, will form if the element has high ionization energy?

High ionization energy means it is difficult to remove electrons. If it is hard to remove electrons, they are not likely to give them away so they will tend to form anions, not cations.

What happens to ionization energy as you move from Li to F? Why?

IE increases due to increasing force from the nucleus. More force means it is more difficult to remove an electron.

Which atom is most likely to give up an electron to form an ion, K or Se? Why?

K because it has a lower ionization energy.

Metals tend to ________ electrons to form a ________ ion.

Lose, positive

Which group of elements, metals or nonmetals, will tend to form ions that are larger than their parent atom?

Metals tend to lose electrons, forming cations. Losing electrons makes the shell smaller so the radius decreases as well.

4. What characteristics are common to all metals? To all nonmetals?

Metals: hard, shiny luster, malleable, ductile, good conductor of heat and electricity. Nonmetals: dull, poor conductors of heat and electricity.

Choose the atom below that will form an ion that is larger than its neutral atom.

Phosphorous

What types of properties were considered when grouping elements for the Periodic Table and how were these properties used to arrange elements?

Physical properties including things such as color, density, and chemical properties such as reactivity. Elements with similar chemical properties are placed in the same group. Elements in different groups may have some similar physical properties but different reactivity.

. What has happened to the blank spaces Mendeleev left in his original Periodic Table?

The discovery of Ga and Ge filled in some of the blanks and validated his theory.

What is the most important factor in determining a trend from top to bottom in a group?

The distance between the valence electrons and the nucleus

1. What happens to the force of attraction between particles as the distance increases between them?

The force decreases.

What happens to the force of attraction between the protons and the electrons as the number of protons increases?

The force increases

3. Which group is most likely to form compounds with the alkali metals?

The halogens. Alkali metals tend to lose one electron to form ions and halogens tend to gain one electron to form ions so these groups bond easily

Why do elements in the same group share the same chemical properties?

They have the same number of valence electrons.

Explain why cations tend to form ions with radii smaller than their neutral atom.

When they lose valence electrons, it increases the effective nuclear charge.

What happens to ionization energy as you move down group 14 from C to Pb? Why?

Your answer should include something about IE decreasing due to a weaker force from the nucleus. Electrons that are farther from the nucleus and experience more shielding are easier to remove.

Explain the relationship between the size of an atoms' radius and its ionization energy as you down a group from Na to Fr

as the radius gets smaller the ionization energy would increase,

The properties of elements reoccur periodically, demonstrating periodic trends when the elements are arranged in order of increasing

atomic number

Mendeleev organized the elements on the Periodic Table by increasing

by increasing atomic mass

How are elements in a period on the modern Periodic Table arranged?

by increasing number of protons

Dimitri Mendeleev

creator of the first periodic table

octet rule

his rule states that a valence shell is full and stable when it contains eight electrons. This is the most stable electron configuration for any atom. Electrons will often transfer to other atoms or be shared between atoms in order to achieve a full valence shell and be chemically stable.

Each time we move from one element to the next across a period, the effective nuclear charge.....

increases by one, but the shielding increases only slightly

What does Zeff do as we move left to right across a period

it increases

How is the atomic radius defined

one-half the distance between the nuclei in a molecule consisting of two identical atoms joined by a covalent bond

An anion (negative ion) is formed by

the addition of one or more electrons to the valence shell of an atom, This results in a greater repulsion among the electrons and a decrease in Zeff per electron

What family contains the most chemically active non-metals?

the halogens

As a general rule, when the elements form cations (positive ions), they do so by

the loss of the one or more valence electrons

as we move down a group.....

the metallic character of the atoms increases

As we go down the elements in a group....

the number of electrons in the valence shell remains constant, but the number of energy levels increases by one each time.

The periodic law

the properties of the elements are periodic functions of their atomic numbers. A modern Periodic Table arranges the elements in increasing order of their atomic numbers and groups atoms with similar properties in the same vertical column. Each box represents an element and contains its atomic number, symbol, average atomic mass, and (sometimes) name. The elements are arranged in seven horizontal rows, called periods or series, and 18 vertical columns called groups. Groups are labeled at the top of each column

What do all members of a group have in common?

valence electrons

As we go across a period from left to right,.....

we add a proton to the nucleus and an electron to the valence shell with each successive element