expected test date thursday feb 5 th -6 th ap chemistry chapter 7 atomic structure and periodicity 1

Expected Test Date Thursday Feb 5 th -6 th AP Chemistry Chapter 7 Atomic Structure and Periodicity 1

What is Atomic Structure and Periodicity? Evidence of the atomic structure How groups and periods show similar properties Most of this has to do with the arrangement of atoms in an element 2

Chapter 7.1 Electromagnetic Radiation Electromagnetic Radiation: Energy that travels through space at the speed of light; examples Light from sun, energy for microwave, X Rays These seem different but they all travel in waves and have specific wavelengths Wavelengths: Distance between two consecutive peaks between wavelengths Symbol 3

Chapter 7.1 Electromagnetic Radiation Frequency: Number of wavelengths per second Symbol v EQUATION TO REMEMBER c = v Given to you on ap exam formula sheet c = speed of light which is 2.998X10ms -1 Speed of light also given to you on AP Chemistry formula sheet 4

Chapter 7.1 Electromagnetic Radiation 5

SA Question 1 on Chapter 7 AP Chem Exam. Book Sample Exercise 7.1 6

Solution 7

7.2 Nature of Matter All matter emits an electromagnetic radiation. At first this made scientists think that matter and energy are the same things however in the early 20 th century Max Planck showed again that energy and matter are the same thing Planck determined that energy can be gained or lost only in whole number multiplies of hv where h is plancks constant 8

7.2 Nature of Matter Equation to know for nature of matter E = nhv E is energy, n is an integer, h is Plancks constant (6.626X10 -34 Js), and v is frequency 9

SA Question 2 on Chapter 7 AP Chem Exam. Book Sample Exercise 7.2 10

Solution 11

7.11 The Aufbau Principal and the Periodic Table Electron configuration 12

7.11 The Aufbau Principal and the Periodic Table What is the electron configuration of stromium? Draw a picture of how electrons move around the nucleus. 13

7.11 The Aufbau Principal and the Periodic Table 14

7.11 The Aufbau Principal and the Periodic Table Aufbau Principle: As protons are added one by one to the nucleus to build up the elements, electrons are similar added to these hydrogenlike orbital's. Hunds rule: the lowest energy configuration for an atom is the one having the maximum number of unpaired electrons. 18

7.11 The Aufbau Principal and the Periodic Table Write the long hand and short hand electron configurations for the following elements Chlorine Argon Potassium 21

SA Question 3 on Chapter 7 Test Know where the s, d, p, and f block elements are and the numbers associated with them. Hence be able to label the periodic table in last slide. Be able to identify an element based on the configuration number i.e. 4s 2 = Calcium 24

SA Question 4 on Chapter 7 Test, sample question 7.7 25

Solution 26

Solution 27

7.12 Periodic Trends Valance electrons = Roman number = s + p number All atoms are unstable until they have 8 valence electrons (same as noble gasses) 1. Answer these questions about the atoms. a. What is the s or the s + p orbitals for the following? b. How many valance electrons does it have? Li = Ne = I = 28

7.12 - Atomic Radius Atomic radius is approximately the distance from the nucleus of an atom to the outside of the electron cloud where the valence electrons are found. The reactivity of the atom depends on how easily the valence electrons can be removed, and that depends on their distance from the attractive force of nucleus. Since protons and electrons are attracted to each other the size of the radius changes based on how many protons there are. Also whenever an s orbital is added the atomic radius increases. 29

7.12 Atomic Radius Think of it like this: Across a period, protons increase. Down a group, s orbitals increase So as you move from left to right across a period, the atomic size? __________ Why? So as you move down a group the atomic size? _________ Why? 30

7.12 Ionization energy Ionization energy is the energy needed to overcome the attraction between the positive charge of the nucleus and the negative charges of the electrons and remove electrons from an atom. Think of ionization energy as how strongly an atoms nucleus holds onto its valence electrons(outermost electrons). A high ionization energy value indicates that an atom has a strong hold on its valence electrons and is less likely to lose its electrons. A low ionization energy indicates that an atom has a weak hold on its valence electrons and is likely to lose one or more electrons. 31

7.12 Ionization energy Think of it like this: If an atoms want to lose an electron it has a low ionization energy. Also if this electrons are far away from protons, it is easier to lose it. So as you move from left to right across a period, the ionization energy? __________ Why? So as you move down a group the ionization energy? _________ Why? 32

7.12 Electronegativity The electronegativity of an element indicates the relative ability of its atoms to attract electrons in a chemical bond. Keep in mind all atoms want 8 total valance electrons. These values are calculated on a number of factors and are expressed in terms of a numerical value of 4.0 or less. The units used to express electronegativities are called Paulings. 33

7.12 Electronegativity Think of it like this: Atoms that want electrons will have a higher electronegativity So as you move from left to right across a period, the electronegativity? __________ Why? So as you move down a group the electronegativity? _________ Why? 34

7.12 Electron Affinity The electron affinity of an element is the energy given off when a neutral atom in the gas phase gains an extra electron to form a negatively charged ion. A fluorine atom in the gas phase, for example, gives off energy when it gains an electron to form a fluoride ion. 35

7.12 Electron Affinity Think of it like this: An atom wants to lose an electron then it will release more energy. So as you move from left to right across a period, the electronegativity? __________ Why? So as you move down a group the electronegativity energy? _________ Why? 36

expected test date thursday feb 5 th -6 th ap chemistry chapter 7 atomic structure and periodicity 1

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