Periodic Trends Notes

Periodic Trends Notes The periodic table organizes all known elements according to their number of protons. The unique shape of the table reveals the ways in which the electrons are organized around the atom in energy levels.

Periodic Trends Notes The structure of an element (especially the number of protons and the number of electrons) will determine the properties of the element (how it will appear, how it will act, etc.) The periodic table can be broken into regions where all the elements in a region have very similar properties. These regions (and subregions) are commonly given names:

Periodic Trends Notes 1. The largest region is the Metals. On page 77, everything in blue is a metal, and they all have certain characteristics in common. They conduct heat and electricity very easily, they are lustrous (shiny) and malleable (can be bent, flattened, etc).

Periodic Trends Notes 2. The second largest region is the Non-metals. These elements (red on page 77) are generally poor conductors of heat and electricity, and when solid are brittle (can be broken or shattered).

Periodic Trends Notes 3. Another region is the Metalloids. These elements (yellow on page 77) have characteristics of metals and non-metals, which vary with the element. (above: selenium, below: silicon)

Periodic Trends Notes 4. Noble gases are located on the far right (green on page 77) and rarely (some never) react with other elements in chemical reactions. This is because they have enough electrons to fill up the p orbital, which makes them very stable.

Periodic Trends Notes **Octet Rule**--This rule states that atoms will be more stable if they have a filled s and p orbitals for their outermost electrons (called valence electrons). Many elements will either lose or gain electrons from other atoms in order to achieve this full “octet” (outermost 8 electrons).

Periodic Trends Notes Rows on the periodic table (horizontal) are called periods. The number of the period will correspond with the energy level of the outermost electron.

Periodic Trends Notes The periodic table can also be broken up into sub-regions called groups. Each column (up/down) is a group, so the far left column is known as group 1, and the far right column (noble gases) is called group 18.

Periodic Trends Notes Typically groups that are next to each other will have similar chemical properties, and the further away two groups are the more different they will be.

Periodic Trends Notes Some groups have names: 1. Group 1 is called the Alkali Metals. They are soft and highly reactive. This is because they have a single electron in their s orbital, which can be lost very easily in chemical reactions, which will make them more stable.

Periodic Trends Notes 2. Group 2 is called the Alkaline-Earth Metals. They are less reactive than Alkali Metals because they have two electrons in the s orbital, which is more difficult to lose in order to be stable. They are also harder and more dense (therefore strong). However, they are still very reactive.

Periodic Trends Notes 3. Groups 3-12 are called Transition Metals. They widely vary in chemical properties. Among the transition metals are the two rows on the very bottom (f orbitals). The first row is called the Lanthanides, and the second row is called the Actinides.

Periodic Trends Notes 4. Group 17 is called the Halogens. These are the most reactive non-metals, because they need only one electron to fill their octet.

Periodic Trends Notes 5. Hydrogen is the only element that composes its own region of the periodic table.

Region/Group Review What group or region of the Periodic Table are the following elements found in? Strontium (Sr, #38) Tantalum (Ta, #73) Curium (Cm, #96) Antimony (Sb, #51) Sulfur (S, #16) 1. Alkaline Earth Metal, 2. Transition Metal, 3. Actinides (Transition Metal) 4. Metalloid, 5. Non-Metal

What physical appearance do they have? Strontium (Sr, #38) Tantalum (Ta, #73) Curium (Cm, #96) Antimony (Sb, #51) Sulfur (S, #16)

More Review Strontium (Sr, #38)

Tantalum (Ta, #73)

Curium (Cm, #96)

Antimony (Sb, #51)

Sulfur (S, #16)

What will they do with their electrons in a chemical reaction? Strontium (Sr, #38) Tantalum (Ta, #73) Curium (Cm, #96) Antimony (Sb, #51) Sulfur (S, #16)

Strontium (Sr, #38)—lose two electrons Tantalum (Ta, #73)—unpredictable Curium (Cm, #96)—unpredictable Antimony (Sb, #51)—gain 3 electrons Sulfur (S, #16)—gain 2 electrons