Chapter 7 (section 2) - Periodic Table

molecule

(in physics and chemistry) a molecule is the simplest structural unit of an element or compound

periodic table

A chart of the elements showing the repeating pattern of their properties

group

A column on the periodic table

period

A horizontal row of elements in the periodic table

chemical symbol

A one or two letter representation of an element an abbreviation or short representation of a chemical element; the symbols in the periodic table The first letter is always capaitlaized.

QUESTION: A element that is very reactive is most likely a member of the: a. noble gases b. alkali metals c. transition metals d. actinides

ANSWER: b, alkali metals Alkali Metals (Group 1; far left side) are the most reactive metals with only one electron in their outer level. Noble gasses (Group 18; far right side), on the other hand, are unreactive, with a full set of electrons in the outer level.

Groups 1 : Alkali Metals

Any metal in Group 1 of the periodic table. Group Contains: Metals Electrons in Outer Level: 1 Reactivity: very reactive Shared properties: softness, color of silver, shininess, low density Alkali metals are the most reactive metals. Atoms of the alkali metals have one electron in their outer level.

GROUP 2: Alkaline-Earth Metals

Any metal in Group 2 of the periodic table. Elements that are classified as Alkaline-Earth metals (Group 2) are less reactive than the alkali metals in Group 1. Why? because they have two electrons in their outer level.

KEY CONCEPT

Elements within each group, or column, on the periodic table have similar properties. WHY? It has to do with electrons. Elements in a group have similar properties because their atoms have the same number of electrons in their outer energy level... which means they will behave in a similarfashion because these electrons in the outer energy level dictate activity and movement

Groups 13-16 of the periodic table

Group 13-16 a mix contains the metalloids and.. some metals and nonmetals. Group 13 is the Boron group (3 electrons in the outer level). Group 14 is the Carbon Level (4 electrons in the outer level). Group 15 is Nitrogen Level (5 electrons in the outter level). Group 16 is the Oxygen level (6 electrons in the outer level).

Name the group that is nonmetal and very reactive

Group 17: Halogens (Flourine, Chlorine, Bromine, Iodine, Astatine)

Name the group that is nonmetal and unreactive

Group 18: Noble gases (full set of electrons in the outer level) (helium, neon, argon, krypton, xenon, radon)

Group 17: Halogens

Halogens are very reactive non-metals. Atoms of the Halogens have 7 electrons in their outer level.

KEY POINT #1

Hydrogen is set off by itself (at the beginning of the table) because its properties do not match the properties of any one group. it is not considered to be a member of group 1 (even though it appears in column 1 above the alkali metals).

Hydrogen is unique

Hydrogen is the most abundant element in the universe. It is set off by itself on the periodic table. its properties do not match the properties of any one group. (one proton; one electron)

Mendeleev

Known for major developments in the periodic table. He arranged the elements by increasing atomic mass. Found that the properties of the known elements followed a pattern that repeated every 7 elements.

KEY POINT #2

Metals are in Groups 1 -16 Metalloids are in Groups 13 -16 Nonmetals are in Groups 14-18 Noble Gases are in Group 18

Group 18: Noble Gases

Noble Gases are unreactive non-metals. Atoms of the Noble Gases have a full set of electrons in their outer shell

noble gas

The Group 18 elements (helium, neon, argon, krypton, xenon, and radon); Noble gases are unreactive

GROUPS 3-12: The Transition metals

These Elements form a bridge between elements on the left and right sides of the periodic table. They take up the middle of the table. They re non-reactive metals. And they are variety of different metals. They include most of the well-known metals... plus the lanthanides and actinides that lie along the bottom of the table

remind me what a metalloid is

a metalloid is an element that has the properties of both metals and nonmetals a metal is an element that is shiny and conducts heat and electricity well a nonmetal is an element or substance that is not metal (they are located on the right side of the table).

halogen

an element found in group 17 of the periodic table (fluorine, chlorine, bromine, iodine, and astatine) They combine with most metals to form salts

transition metals

elements that form a bridge between the elements on the left and right sides of the table. These are also good conductors of thermal energy. elements in groups 3-12

What is the purpose of the zigzag line on the right side of the periodic table.

it divides the metals and nonmetals and also shows where the metalloids are. it's an easy way to locate where the metals, nonmetals and metalloids are located on the table

alkali metal

one of the elements of Group 1 of the periodic table (lithium, sodium, potassium, rubidium, cesium, and francium). These are the most reactive metals

alkaline earth metal

one of the elements of Group 2 of the periodic table... they are highly reactive ( beryllium, magnesium, calcium, strontium, barium, and radium). They have two electrons in their outer level.

How do the physical and chemical properties of the elements change?

periodically across each group

atomic number

the number of protons in the nucleus of an atom