Year 11 ATAR Chemistry: Trends in the Periodic Table PDF

Daily Review What are the names of the following elements? Ag Cu F C Na Fe Zn Mn Mg Sr Be Au What are the symbols of the following elements? Potassium Chromium Aluminium...

Daily Review What are the names of the following elements? Ag Cu F C Na Fe Zn Mn Mg Sr Be Au What are the symbols of the following elements? Potassium Chromium Aluminium Calcium Bromine Tungsten Argon Yttrium Trends or the Periodic Table Year 11 ATAR Chemistry Learning Objective To describe and explain the trends that occur across the periods and down the groups of the Periodic Table. Success Criteria I will be able to: Define the terms ‘first ionisation energy’ and ‘electronegativity’. Explain how and why ionisation energy and electronegativity trend in the Periodic Table. Explain how and why metallic character and atomic radius trend in the Periodic Table. Activate Prior Knowledge What is the first thing to consider when trying to quickly find the following elements in the Periodic Table? A. Magnesium B. Chlorine Concept Development CFU Use this box for CFU What is a trend? questions. In the context of the periodic table, a trend refers to a predictable pattern or change in certain properties of elements as you move across a row (period) or down a column (group). These trends can be used to explain the physical and chemical properties that occur in different elements. They also help to indicate the reasons for why an element sits in a particular spot of the Periodic Table. Concept Development Demonstration: reactive metals. Lithium, sodium and potassium are all elements in group 1 of the DEMO Periodic Table. They react violently when placed in water. Observe the reaction of each and answer the following: 1. What are their differences in reactivity? 2. Can you explain reasons (in terms of atomic structure) why this is the case? Potassium > Sodium > Lithium. Potassium has a larger atomic radius which means it requires less energy to remove its valence electron and allow it to react. Concept Development CFU What is ‘first ionisation First ionisation energy. energy’? The first ionisation energy of an element refers to the quantity of energy that would be required to remove the first electron from CFU its atoms. What determines the first ionisation energy of an An element that is going to have a small first ionisation energy element? is one of few electrons. This is due to the element’s atoms preferring to lose electrons to become stable. An element that is going to have a large first ionisation energy is one of many electrons. This is due to the element’s atoms preferring to gain electrons to become stable. Concept Development CFU How does first ionisation Trend in first ionisation energy. energy trend across a period? Across a period: The first ionisation energy of an element increases from left to right across the Periodic Table. CFU This is because there is an increase in the number of protons, which increases the positive nature of the nucleus. This increases the pull on the How does first ionisation electrons by the nucleus and more energy would be needed to remove one. energy trend down a group? Down a group: The first ionisation energy decreases down a group of the Periodic Table. This is because with more energy levels, the valence electrons are a greater distance from the nucleus. They are not as tightly held by the nucleus and would require less energy to remove them. Concept Development Concept Development Concept Development CFU What is meant by Electronegativity. ‘electronegativity’? Electronegativity is defined as the tendency of an atom to attract electrons in a chemical bond. It reflects how strongly an atom can CFU pull shared electrons towards itself when forming compounds. What determines the electronegativity of an An element with high electronegativity is one that only needs a element? few electrons to ‘fill’ its valence shell (non-metals) and has a small atomic radius. An element with low electronegativity is one that loses electrons to fill its valence shell (metals) and has a large atomic radius. Concept Development Concept Development CFU Trends in electronegativity. How does electronegativity trend across a period? Across a period: The electronegativity of an element increases from left to right across a period. Across a period, the higher positive charge attracts the electrons in the outer CFU shell more strongly, making it easier for the atom to pull electrons towards itself in a bond. How does electronegativity The shielding effect (the repulsion between inner electrons and outer electrons) trend down a group? does not increase. As a result, the effective nuclear charge felt by the outer electrons increases, enhancing the atom’s ability to attract electrons. Down a group: The electronegativity of an element decreases down a group. The number of electron shells increases, meaning that the outermost electrons are farther from the nucleus. This weakens the attraction between the nucleus and the electrons, making it harder for the atom to attract additional electrons. With more inner electron shells, the inner electrons repel the outer electrons. This shielding effect reduces the effective nuclear charge that the outer electrons experience. As a result, the ability of the nucleus to attract electrons diminishes, leading to lower electronegativity. Concept Development Concept Development CFU How does metallic Trends in metallic character. character trend in the Periodic Table? Across a period: The metallic character of an element decreases from left to right across a period. Down a group: The metallic character of an element increases down a group. Concept Development CFU Trends in atomic radius. How does atomic radius trend across a period? Across a period: The atomic radius of an element’s atoms decreases from left to right across the Periodic Table. CFU As you move across a period, the nucleus is more positive which attracts the electrons more strongly, pulling them closer to the nucleus. Due to the How does atomic radius stronger attraction, the overall size of the atom decreases, leading to a trend down a group? smaller atomic radius. Down the group: The atomic radius of an element’s atoms increases down a group of the Periodic Table. As you move down a group, each successive element has an additional electron shell. This means that the outermost electrons are located further from the nucleus, resulting in a larger atomic radius. Lesson Closure 1. What is ‘first ionisation energy’? 2. What is ‘electronegativity’? 3. Explain the trends of first ionisation energy in the Periodic Table. 4. Explain the trends of electronegativity in the Periodic Table. 5. Explain the trend of metallic character in the Periodic Table. 6. Explain the trend of atomic radius in the Periodic Table. Lesson Closure Define the terms ‘first ionisation energy’ and ‘electronegativity’. Explain how and why ionisation energy and electronegativity trend in the Periodic Table. Explain how and why metallic character and atomic radius trend in the Periodic Table. Questions Set 9 Questions 4 Set 15 Questions 1,2,3,4,5,7