Term
| When we refer to a period on the periodic table, is that a row or a column? |
|
Definition
| A period is a row of elements. |
|
|
Term
| When we refer to groups or families on the periodic table, what does that mean? |
|
Definition
| A group or a family on the periodic table is a column of elements. |
|
|
Term
| There are seven periods in the periodic table and they represent what? |
|
Definition
| Each of the periods 1-7 on the periodic table represents the principle quantum number n=1 through n=7. |
|
|
Term
| Groups/families on the periodic table include elements that have the same electronic configuration in their valence shell. These elements also share ____. |
|
Definition
| Since they have the same number of electrons (in their valence shell) to interact with other molecules/elements they have similar chemical properties. |
|
|
Term
| Why do valence electrons form chemical bonds? |
|
Definition
| They form bonds because of their higher potential energy and the fact they are held less tightly by the nucleus. |
|
|
Term
| True or False: Valence electrons determine the chemical reactivity of the molecule. |
|
Definition
|
|
Term
| What is the effective nuclear charge? What is its trend on the periodic table? |
|
Definition
| The effective nuclear charge (Zeff) is the amount of positive charge (from the protons in the nucleus) that pulls on the orbiting valence electrons. It increases from left to right for elements within the same period (row). It is constant among elements with the same group due to the shielding effect of additional layers of inner electrons. Remember, the shielding effect occurs because electrons in the outermost layer are being pulled inward by the nucleus but also being repelled by the inner layers of orbiting electrons. The more layers of electrons you have, the more repelling forces the outermost electrons will experience. This will cause the valence electrons to experience less of an attractive force from the nucleus and therefore the nucleus will pull less on those valence electrons than it will pull on electron layers that are closer to the nucleus. |
|
|
Term
| How does the atomic radius change as you move from left to right across a period. Why does this change occur? |
|
Definition
| As you move from left to right ----> across a period, the atomic radius decreases. This occurs because as you move from left to right, more protons and electrons are added to the elements. As the nucleus gains more positive charge, it holds its electrons more closely/tightly and this decreases the atomic radius. |
|
|
Term
| Elements generally gain or lose electrons to obtain the stable ____ formation that the ____ gases have. |
|
Definition
| Elements generally gain or lose electrons to obtain the stable octet formation that the inert noble gases have. |
|
|
Term
| When electrons are added to an element, are they added to the outter or inner shell? |
|
Definition
| Electrons are added to the outermost shell and the numer of inner-shell electrons (which acts as insulation) remains constant. |
|
|
Term
| What are the periodic trends for Zeff and atomic radius? |
|
Definition
Zeff increases from ----> there is no change going up and down the groups/families (columns)
Atomic radius decreases -----> and increases going down a group/family.
[image] |
|
|
Term
| What is ionization energy? |
|
Definition
| Ionization energy (IE) is the energy required to remove an electron completely from a gaseous atom or ion. Ionization increases for smaller atoms and decreases for larger atoms (depends on how much the nucleus pulls on the surrounding electrons). |
|
|
Term
| Is removal of an electron from an atom an endothermic or exothermic process? |
|
Definition
| Removing an electron always requires an input of energy and is always endothermic. |
|
|
Term
| What are the periodic trends for ionization energy? |
|
Definition
Ionization energy increases from left to right and from bottom to top. Notice this corresponds to the trend in atomic radii. The larger the radius, the easier it is to pluck an electron off of an atom.
[image] |
|
|
Term
| Which two kinds of elements are the least likely to give up electrons/ have the highest ionization energies? |
|
Definition
| The halogens don't like to give up electrons, neither do the noble gases. Noble gases are elements with the highest ionization energies. |
|
|
Term
| The energy necessary to remove the first electron is called the first _____ and the energy necessary to remove the seond electron is called the second _____. |
|
Definition
| The first and second ionization energies. The more electrons you remove, the harder it becomes to remove additional electrons. |
|
|
Term
| Is gaining an electron an endothermic or exothermic process? |
|
Definition
| Gaining an electron causes a release of energy and is always an exothermic process. |
|
|
Term
| What is electron affinity? |
|
Definition
| Electron affinity is the amount of energy released when an electron is added to a neutral atom to form a negative ion. It applies only to atoms in their gaseous states. The amount of energy given off increases the stronger the Zeff. |
|
|
Term
| What is the periodic trend for electron affinity? |
|
Definition
| The trend for electron affinity is identical to the trend for ionization energy. It increases from left to right and it increases from bottom to top. It is opposite to the trend in increasing atomic radius. |
|
|
Term
| What are the electron affinities of the noble gases like? |
|
Definition
| The noble gases have electron affinities on the order of zero b/c of their stable octets. They cannot readily accept an electron. |
|
|
Term
| What is electronegativity and what is its periodic trend? |
|
Definition
| Electronegativity is a measure of the tendency of an atom to attract a bonding pair of electrons. The trend for electronegativity is the same as the trend for ionization energy and electron affinity. It increases from left to right and from bottom to top. |
|
|
Term
| What are the characteristics of metals? |
|
Definition
| Metals have the ability to be hammered into shape (malleability) and the ability to be drawn into wires (ductility). At the atomic level they have low effective nuclear charge (Zeff), low electronegativity, large atomic radius and low ionization energy. Metals can fairly easily give up one or more electrons. This loose hold on valence electrons is what makes metals good conductors of heat and electricity. |
|
|
Term
Be able to identify metals on the periodic table:
[image] |
|
Definition
THE ALKALI METALS: The alkali metals, found in group 1 of the periodic table (formerly known as group IA), are very reactive metals that do not occur freely in nature. These metals have only one electron in their outer shell. Therefore, they are ready to lose that one electron in ionic bonding with other elements. As with all metals, the alkali metals are malleable, ductile, and are good conductors of heat and electricity. The alkali metals are softer than most other metals. Cesium and francium are the most reactive elements in this group. Alkali metals can explode if they are exposed to water.
THE ALKALI EARTH METALS: The alkaline earth elements are metallic elements found in the second group of the periodic table. All alkaline earth elements have an oxidation number of +2, making them very reactive. Because of their reactivity, the alkaline metals are not found free in nature.
THE TRANSITION METALS: The 38 elements in groups 3 through 12 of the periodic table are called "transition metals". As with all metals, the transition elements are both ductile and malleable, and conduct electricity and heat. The interesting thing about transition metals is that their valence electrons, or the electrons they use to combine with other elements, are present in more than one shell. This is the reason why they often exhibit several common oxidation states. There are three noteworthy elements in the transition metals family. These elements are iron, cobalt, and nickel, and they are the only elements known to produce a magnetic field.
THE LANTHANIDE AND ACTINIDE SERIES:
The Lanthanide series can be found naturally on Earth. The Actinide series are all radioactive and some are not found in nature. |
|
|
Term
| What are the characteristics of nonmetals? |
|
Definition
| They have high ionization energies, electron affinities and electronegativities. They have small atomic radii and are poor conductors. They include Hydrogen, the halogens, the noble gases and the elements to the right of the stair step that includes carbon. |
|
|
Term
| What are the characteristics of metalloids? |
|
Definition
| Metalloids form the staircase with boron and also include Ge and Sb. They possess characteristics of both metals and nonmetals. |
|
|
Term
| What are the characteristics of halogens and noble gases? |
|
Definition
| Halogens are highly reactive with 7 valence electrons. They are desperate to complete their octets by each gaining one electron to become like the noble gases. The noble gases have low chemical reactivities as a result of their filled valence shells. They have high ioniziation energies and little or no tendency to gain or lose electrons. |
|
|
