The Periodic Table



The Periodic Table

Chapter 6

I. Organizing the Elements

Chemist used of elements to sort them into groups. One of the first periodic tables organized the elements in increasing order of .

A. - Elements with similar chemical properties appear at regular intervals when listed in order of increasing . In the periodic table elements are arranged in order of increasing atomic number.

B. Metals, Nonmetals, and Metalloids

1. Metals are located to the of the stair step line. Metals are shiny, conduct heat and energy

a) Metals are – can be drawn into a wire.

b) Metals are – they can be hammered into shape.

c) Metals have high .

d) Metals have high .

1 Nonmetals of the stair step line.

a) Nonmetals are conductors of heat and energy

b) Nonmetals have density many nonmetals are gases at room temperature.

c) Nonmetals have low compared to metals.

2. Metalloids, also called , have properties of both metals and nonmetals. are all semimetals.

Classifying the elements

The periodic table displays the symbols of the elements along with information about the structure of their atoms.

A. Group Names on the Periodic Table. on the periodic table are called groups and families

1. – group IA except hydrogen (see page 162-163 text book)

2. metals – group IIA

3. – group VIA

4. – group VIIA. These are the most reactive

5. – group VIIIA These are the least reactive

B. – all the columns with an “A.” They are called the representative elements because they display a wide range of physical and chemical properties.

C. – all the middle area

D. Elements can be sorted into noble gases, representative elements, transition metals, or inner transition metals based on their . (See chart p.166)

Periodic Trends

4 within a group as the atomic number

. Group on the periodic table is a . Period on the periodic table is a . Atomic radius within a period as the atomic number . As you go across the table the size decreases.

E. are atoms that have either a negative or positive charge. This happens when an atoms gains or loses electrons. When an atom loses an electron the ion is said to have a charge and is called a . When an atom gains an electron it is said to have a charge and is called an

1. Cations are than the atoms since they have fewer electrons.

2. Anions are the atoms since they have more electrons.

F. is the amount of energy required to remove an electron from an atom.

1. Ionization energy (IE) as you go down the periodic table, this is because as you get electron further away from the its attraction to the nucleus decreases, so the electron can be removed easier. Ionization increases as you go to the left from the right.

2. has the highest I E

3. has the smallest I E

G. Electron affinity – amount of energy given off when atom an electron.

1. When atom has an extra electron it is called an .

Cl + e- ( Cl- + energy

2. Electron affinity as you go up and to the right.

3. has the highest electron affinity

H. Electronegativity

1. The ability of an atom of an element to to itself.

2. Defined as the difference between ionization energy (IE) and electron affinity (EA)

I E – E A

2

3. Increases as you go up and to the

4. is the most electronegative.

I. When ions have the same number of electrons they are said to be (isomers).

Example: F- and Na+. In this case both ions would have electrons.

6 . Some elements exist as a compound in nature. These are elements that are bounded to an element of same type. They are H2, N2, O2, F2, Cl2, Br2, I2. There are a total of .

Questions

1. Identify each element as a metal, metalloid, or nonmetal.

a. gold ____________

b. silicon ___________

c. sulfur ____________

d. barium ____________

2. Identify each property below as more characteristic of a metal or a nonmetal.

a. a gas at room temperature ______________

b. brittle _______________

c. malleable ________________

d. poor conductor of electric current ____________________

e. shiny ________________

3. Where are the alkali metals, the alkaline earth metals, the halogens, and the noble gases located in the periodic table? ________________________________________________________________________

_______________________________________________________________________.

4. Which element in each pair has atoms with a larger atomic radius? (circle the correct element)

a. sodium or lithium

b. strontium or magnesium

c. carbon or germanium

d. selenium or oxygen

5. Which element in each pair has a higher electronegativity value?

a. Cl or F

b. C or N

c. Mg or Ne

d. As or Ca

6. When do ions form? _________________________________________________

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