Chemical Families Chemistry 5(B) Knowing the properties of each chemical family on the periodic table will help you utilize the periodic table. Chemical Families Chemistry 5(B)

Chemical Families Lesson Objectives Identify and explain the properties of chemical families in the periodic table Alkali metals Alkaline earth metals Transition metals Halogens Noble gases This presentation will teach you how to identify and explain the properties of chemical families in the periodic table, including the alkali metals, alkaline earth metals, transition metals, halogens, and the noble gases.

The Periodic Table Periodic table – table that displays the elements in order of increasing atomic number and organizes them according to chemical properties Elements arranged in a periodic pattern Behavioral trends of an element can then be predicted by knowing its position on the table The periodic table displays the elements in order of increasing atomic number and organizes them according to chemical properties. Since elements are arranged in a “periodic” pattern, behavioral trends of an element can then be predicted by knowing its position on the table.

The Periodic Table The periodic table pictured can be broken down into sections and studied in more detail. By learning the organization of the periodic table and why it is arranged in this manner, we can learn more about elements’ physical attributes as well as their behavioral patterns based on their location on the table.

Periods and Groups Periodic table is arranged in Periods – rows on the periodic table Groups – columns on the periodic table Also called families, since elements in groups share similar chemical properties The periodic table is arranged into seven periods or rows, as well as 18 groups or columns. Groups are also called families, since elements in groups share similar chemical properties.

Numbering Groups Groups are numbered 1–18 or 1–8 with A/B notation Tall columns are notated as “A” Main group elements Short columns are notated as “B” 1A 2A 3A 4A 5A 6A 7A 8A 3B 4B 5B 6B 7B 8B 1B 2B Groups are numbered either one through eighteen or one through eight with an “A” notation given to the tall columns and “B” notation to the short columns. Group A elements are known as the main group elements. Main group elements tend to show periodic patterns most clearly and consistently. Main Group Elements

Chemical Families Family names Group 1A –– alkali metals Group 2A –– alkaline earth metals Group 7A –– halogens Group 8A –– noble gas Group 1–8B –– transition metals 1A 2A 3A 4A 5A 6A 7A 8A 3B 4B 5B 6B 7B 8B 1B 2B Family names may also be used instead of group numbers. Group 1A elements are known as the alkali metals; group 2A elements are the alkaline earth metals; group 7A elements are the halogens and the group 8A elements are the noble gases. The short groups in the middle of the table, groups 1–8B, are collectively called the transition metals.

Decoding the Periodic Table Arrangement of elements on periodic table help predict physical and chemical properties including Physical state Boiling, melting, or freezing point Density Metallic and nonmetallic character Reactivity Likelihood of gaining or losing electrons Valence – number of electrons in the atom’s valence or outermost energy level The arrangement of elements on the periodic table can help us predict their physical and chemical properties. Trends in physical and chemical properties shown by the periodic table include trends in the physical state of the element, its boiling, melting, or freezing point, its density, its metallic or nonmetallic character, its reactivity, its likelihood of gaining or losing electrons, and its valence. Valence is the number of electrons in the atom’s valence or outermost energy level.

Metals, Nonmetals, and Metalloids Step-wise line that begins at the element boron and moves downward in a zigzag pattern divides the table Metals are to the left of the line Nonmetals are to the right of the line Along the line are the metalloids Possess properties of both metals and nonmetals Metalloids The periodic table may be divided into a left half and right half using a step-wise line that begins at the element boron and moves downward in a zigzag pattern. To the left of the line are the metals and to right are nonmetals. Along the line are the semi-metals or metalloids, shown in blue in the image, which possess properties of both metals and nonmetals.

Metallic and Nonmetallic Character Metals tend to lose electrons to form cations Cations – positively charged particles Other properties of metals Lustrous, good conductors, malleable, and ductile Nonmetals gain electrons to form anions Anions – negatively charged particles Other properties of nonmetals Many are gases at room temperature, solids are usually brittle, and are typically poor conductors We can derive general information about an element simply by looking to the table to see if it is a metal or nonmetal. Metals tend to lose electrons to form cations or positively charged particles. Metals are lustrous, good conductors of electricity, malleable, and ductile. Nonmetals, on the other hand, gain electrons to form anions or negatively charged particles. Many nonmetals are gases at room temperature, brittle as solids, and are typically poor conductors.

Chemical Properties Elements in the same group will have similar chemical properties Group number of group A elements equals the number of valence electrons Valence electrons – electrons in the valence or outermost energy level, which are most likely to be lost, gained, or shared Determines the oxidation number of an element Positive if electrons are lost Positive charge equals the number of electrons lost Negative if electrons are gained Negative charge is equal in magnitude to the number of electrons gained Chemical properties tell us about how elements in a group react, or how they will behave with other elements. Elements in the same group, or family, will have similar chemical properties. The group number of group A elements can tell us many things, such as the number of valence electrons, which are the electrons in the valence or outermost energy level. They are the electrons that are most likely to be lost, gained, or shared. The group number of group A elements also determines the oxidation number, or charge of an element as an ion. The oxidation number is positive if electrons are lost. The positive charge is equal to the number of electrons lost. The oxidation number is negative if electrons are gained. The magnitude of the charge is equal to the number of electrons gained.

Chemical Properties Reactivity is determined by the ability to gain, lose, or share electrons in order to achieve an octet Octet – eight electrons in the valence energy level Noble gases naturally have an octet Extremely low reactivity Other groups attempt to achieve octets by gaining, losing, or sharing electrons Higher reactivity Types of elements involved in the reaction will determine how the octet is achieved Metals tend to lose electrons when reacting with nonmetals Nonmetals tend to gain electrons when reacting with metals and share electrons when reacting with other nonmetals Reactivity is also determined by the ability to gain, lose, or share electrons in order to achieve an octet. An octet is achieved when there are eight electrons in the valence energy level. Noble gases naturally have an octet and therefore, have extremely low reactivity. Other groups attempt to achieve octets by gaining, losing, or sharing electrons. This means that they have higher reactivity than the noble gases. The types of elements involved in the reaction will determine how the octet is achieved. When reacting with nonmetals, metals tend to lose electrons to attain octet. On the other hand, nonmetals tend to gain electrons when reacting with metals and share electrons when reacting with other nonmetals.

By Felix Burton (Flickr) [CC-BY-2.0] Noble Gases Noble gases Gases at room temperature Relatively inert Have full valence shells Typically don’t form ions 8A 18 By Felix Burton (Flickr) [CC-BY-2.0] The first group we will discuss is Group 8A, the noble gases. These elements are gases at room temperature. They are relatively inert or nonreactive because they already have full valence shells. Therefore, noble gases don’t typically lose or gain electrons to form ions. The noble gases include helium, neon, argon, krypton, xenon, and radon. Noble gases such as neon gas are commonly used in so called “neon signs.”

Halogens Halogens Highly reactive nonmetals Seven valence electrons One electron away from having an octet Gain one electron to achieve octet Ions have -1 charge Very electronegative Electronegative – possessing the ability to acquire electrons readily Form ionic bonds by accepting electrons from metals Form covalent bonds by sharing electrons with other nonmetals Combine with H+ to form acids 7A 17 Group 7A, the halogens, are highly reactive nonmetals containing seven valence electrons. In other words, they are one electron shy of an octet. They gain an electron to complete their octet and have a -1 charge as ions as a result. Because they are very close to achieving an octet, they are very electronegative or possess the ability to acquire electrons readily. Halogens form ionic bonds by accepting electrons from metals and covalent bonds by sharing electrons with other nonmetals. Halogen ions also combine with hydrogen ions to form acids in solutions. The halogens include fluorine, chlorine, bromine, iodine, and astatine.

Alkaline Earth Metals Alkaline earth metals Highly reactive metals Two valence electrons Two electrons away from having an octet Loses two electrons to attain octet Ions have +2 charge Form oxides by combining with oxygen Form ionic bonds with nonmetals, creating salts Combine with OH– to form bases 2A 2 Group 2A, the alkaline earth metals, are also highly reactive. They contain two valence electrons and are two electrons away from having an octet. They lose their two valence electrons to attain their octet, giving their ions a +2 charge. Alkaline earth metals form oxides by combining with oxygen. They can also form ionic bonds with nonmetals to create salts. Ions of alkaline earth metals combine with hydroxide ions to form bases in solutions. The alkaline earth metals include beryllium, magnesium, calcium, strontium, barium, and radium.

Alkali Metals Alkali Metals Highly reactive metals One valence electron One electron away from having an octet Lose one electron to attain an octet Ions have +1 charge Form oxides by combining with oxygen Form ionic bonds with nonmetals, creating salts Combine with OH– to form strong bases 1A 1 Group 1A, the alkali meals, are highly reactive metals with one valence electron. They are one electron away from forming an octet. They readily lose one electron in order to attain an octet and form ions with +1 charge as a result. Just like the alkaline earth metals, alkali metals form oxides by combining with oxygen and create salts by forming ionic bonds with nonmetals. Ions of alkali metals also combine with hydroxide ions to form strong bases in solutions. The alkali metals include lithium, sodium, potassium, rubidium, cesium, and francium.

Transition Metals Groups 1–8B are collectively called the transition metals Transition in oxidation numbers Form different compounds with nonmetals as a result of variance in charges Less reactive than alkali metals or alkaline earth metals 3B 4B 5B 6B 7B 8B 1B 2B 3 4 5 6 7 8 9 10 11 12 The 10 short columns in the middle of the periodic table, groups I-VIIIB are collectively called the transition metals. They vary or transition in oxidation number even within the same group. Therefore, transition metals can form different compounds with nonmetals as a result of the variance in charges. For example, iron can have a oxidation number of either +2 or +3. Therefore, iron can form either iron(III) oxide, which has the formula Fe2O3, or iron(II) oxide, which has the formula FeO, when combined with oxygen. While they are still reactive, transition metals are less reactive than alkali metals or alkaline earth metals. Examples of transition metals include familiar metals such as iron, gold, copper, nickel, and silver.

Chemical Families Lesson Objectives Identify and explain the properties of chemical families in the periodic table Alkali metals Alkaline earth metals Transition metals Halogens Noble gases This concludes our presentation on the chemical families. You now know how to identify and explain the properties of chemical families in the periodic table, including the alkali metals, alkaline earth metals, transition metals, halogens, and the noble gases.