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Periodic Trends Elemental Properties and Patterns.

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Presentation on theme: "Periodic Trends Elemental Properties and Patterns."— Presentation transcript:

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2 Periodic Trends Elemental Properties and Patterns

3 Periodic Table Periodicity: regular variations (or patterns) of properties with increasing atomic number. Both chemical and physical properties vary in a periodic (repeating) pattern. Group: vertical column of elements (“family”) Period: horizontal row of elements

4 Chemistry: The Periodic Table and Periodicity 1. Who first published the classification of the elements that is the basis of our periodic table today? 2. By what property did Mendeleev arrange the elements? 3. By what property did Moseley suggest that the periodic table be arranged? 4. What is the periodic law? 5. What is a period? How many are there in the periodic table? 6. What is a group (also called a family)? How many are there in the periodic table? DMITRI MENDELEEV ATOMIC MASS ATOMIC NUMBER THE PROPERTIES OF THE ELEMENTS REPEAT PERIODICALLY A HORIZONTAL ROW IN THE PERIODIC TABLE; 7 A VERTICAL COLUMN IN THE PERIODIC TABLE; 18 Periodic Table and Periodicity

5 The Periodic Law Mendeleev understood the ‘Periodic Law’ which states: When arranged by increasing atomic number, the chemical elements display a regular and repeating pattern of chemical and physical properties.

6 Metals, Nonmetals, & Metalloids Metals Metalloids Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 349 Nonmetals

7 Transition metals alkali metals alkaline earth metals halogens noble gases lanthanides actinides Elements with similar chemical behavior are in the same group.

8 Metals Metals are lustrous (shiny), malleable, ductile, and are good conductors of heat and electricity. They are mostly solids at room temp. What is one exception? Mercury (Hg)

9 Nonmetals Nonmetals are the opposite. They are dull, brittle, nonconductors (insulators). Some are solid, but many are gases, and Bromine is a liquid.

10 Metalloids Metalloids, aka semi-metals are just that. They have characteristics of both metals and nonmetals. They are shiny but brittle. And they are semiconductors. What is our most important semiconductor?

11 Periodic trends Identifying the patterns

12 Metallic Characteristics metallic character increases

13 Chemistry: The Periodic Table and Periodicity 1. Who first published the classification of the elements that is the basis of our periodic table today? 2. By what property did Mendeleev arrange the elements? 3. By what property did Moseley suggest that the periodic table be arranged? 4. What is the periodic law? 5. What is a period? How many are there in the periodic table? 6. What is a group (also called a family)? How many are there in the periodic table? DMITRI MENDELEEV ATOMIC MASS ATOMIC NUMBER THE PROPERTIES OF THE ELEMENTS REPEAT PERIODICALLY A HORIZONTAL ROW IN THE PERIODIC TABLE; 7 A VERTICAL COLUMN IN THE PERIODIC TABLE; 18 Periodic Table and Periodicity

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15 Experiment Variable – factor in the experiment that is being tested

16 The factor that is changed is known as the independent variable (IV). –Also referred as “The Cause” The factor that is measured or observed is called the dependent variable (DV). –Also referred as “The Effect”

17 Rule for Addition and Subtraction Calculating with Numbers Written in Scientific Notation In order to add or subtract numbers written in scientific notation, you must express them with the same power of 10. Sample Problem: Add 5.8 x 10 3 and 2.16 x 10 4 (5.8 x 10 3 ) + (21.6 x 10 3 ) =27.4 x 10 3 Exercise: Add 8.32 x and 1.2 x x x 10 4

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20 ++ Particles with opposite charges attract one another. Particles with like charges repel one another

21 Depends on: 1. Amount of charge 2. Distance between charges

22 Periodic Trends atomic radius. Radius is the distance from the center of the nucleus to the “edge” of the electron cloud.

23 Atomic Radii

24 Trend: decreases across a period WHY??? – As the # of protons in the nucleus increases, the positive charge increases and as a result, the “pull” on the electrons increases. Trend: increases down a group WHY??? – The atomic radius gets bigger because electrons are added to energy levels farther away from the nucleus decreasing the “pull” or force of attraction.

25 Atomic Size Trends

26 Ionization Energy Definition: energy required to remove outer electrons from an atom

27 Hungry for Tater Tots? Mr. C at 7 years old.

28 OUCH!!

29 Ionization Energy Trend: increases across a period WHY??? All the atoms in the same period – Increasing the number of protons increase the “pull” or force of attraction. Trend: decreases down a group WHY??? – Electrons are further away from the positive “pull” of the nucleus and therefore easier to remove.

30 First Ionization energy Atomic number HeNe Ar Kr H Li Na K Rb

31 Electronegativity Definition: the tendency of an atom to attract electrons to itself when chemically combined with another element

32 Trend: increases across a period (noble gases excluded!) WHY??? – Nuclear charge is increasing, atomic radius is decreasing; attractive force that the nucleus can exert on another electron increases. Electronegativity Trend: decreases down a group WHY??? – The electrons are farther away from the nucleus; decreased attraction, so decreased electronegativity

33 ElectronegativityTrends

34 Summing Up Periodic Trends

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36 Which has the largest atomic radius? 7. Br - Br 8. Al + Al As an atom gains electrons, the atom gets bigger As an atom loses electrons, the atom gets smaller


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