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The Periodic Table is a list of the chemical elements in order of increasing atomic number. It was first published in 1869 by Russian chemist Dmitri Mendeleev, who predicted that one day there would be a table with all the known elements. He also predicted that there would be gaps between some of the elements and these gaps were filled over time.
The chapter 6 chapter assessment the periodic table and periodic law answer key is a chapter in a book that covers the topics of atoms, chemical reactions, and how to use the periodic table. The chapter has an answer key at the end that includes all questions in the chapter.
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In the previous chapter, we covered the properties of the elements on the periodic table. This chapter will focus on how these properties are used to form laws. We will begin with a review of atomic mass and period.
Atomic Mass: Theatomic mass is a fundamental property that determines an element’s weight. All elements have an atomic mass, which is determined by the number of protons in the nucleus. Elements with more protons have a higher atomic mass than elements with fewer protons.
Period: Period is another fundamental property that relates an element’s characteristics to its place on the periodic table. Each element has a specific period, or number of electrons around its nucleus. The higher an element’s period, the lower its ionization energy (the amount of energy it takes to break down an atom into ions). That means that elements with shorter periods are more reactive and can form compounds more easily than elements with longer periods.
The Periodic Table
The periodic table is a chart that shows how elements are related to one another. The columns of the periodic table are called groups, and the rows are called periods. The elements in each group have similar properties. The elements in each period have different properties.
The first element in each period is called the representative element. The representative element for period 2 is lithium (Li). The representative element for period 3 is sodium (Na). The representative element for period 4 is potassium (K).
The atomic radii of the representative elements in periods 2, 3, and 4 can be graphed as follows:
Period 2: Li Na K Rb Cs
atomic radius (pm) 167 188 227 247 265
Period 3: Mg Al Si P S Cl Ar
atomic radius (pm) 145 118 111 98 88 79 71
Graphical representation of data with error bars Atomic radius vs Period number
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The Periodic Law
The periodic law is the law that states that elements are arranged in the periodic table according to their atomic numbers. This means that elements with similar properties are found in the same column of the periodic table. The periodic law is used to predict the properties of elements based on their position in the periodic table.
The Atomic Radii of Representative Elements:
Atomic radii can be used to predict the properties of elements. In general, smaller atoms have higher electronegativity, while larger atoms have lower electronegativity. This trend is due to the increasing number of protons in an atom’s nucleus; as more protons are added, they exert a greater force on the electrons, making it harder for them to escape. As a result, smaller atoms are more likely to form covalent bonds, while larger atoms are more likely to form ionic bonds.
The Properties of the Periodic Table:
The periodic table is a tool that scientists use to organize and understand chemical elements. The elements are arranged in order of increasing atomic number, which corresponds to increasing number of protons in the nucleus. The columns of the periodic table represent groups of elements with similar properties, while the rows represent periods during which those properties change regularly.
The Elements
The periodic table is a tabular arrangement of the chemical elements, organized on the basis of their atomic numbers, electron configurations, and recurring chemical properties. Elements are placed in groups (columns) in the periodic table.
Period 2:
The second period contains elements with 2 valence electrons. The first 18 elements are in this period. They are lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr). The alkali metals make up Group 1A, while Groups 2Aufffd2F are the transition metals. Lithium is soft enough to be cut with a butter knife, while cesium is so reactive that it explodes on contact with water. Potassium burns with a purple flame, whereas sodium burns yellow.
Period 3:
The third period contains elements with 3 valence electrons. The first 28 elements are in this period. They are scandium (Sc), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni). The first four rows of transition metals are often collectively referred to as the d-block because these elements have d orbitals in their outermost electron shells where they can hold up to 10 electrons each. All of these metals except for zinc have at least one common oxide compound where they exhibit a +2 oxidation state; zinc only forms compounds in its +1 oxidation state. Iron rusts when it comes into contact with oxygen and moisture, but chromium does not because it forms an oxide film that protects the metal from further reaction. Nickel is used in alloys like stainless steel because it imparts corrosion resistance and strength to the metal.
Period 4:
The fourth period contains elements with 4 valence electrons ufffd the maximum number possible for any element without filling d orbitals in its outermost electron shell . The first 36 elements are in this period . They include yttrium(Y) , zirconium(Zr) , niobium(Nb) , molybdenum(Mo) , technetium(Tc) , ruthenium(Ru) , rhodium(Rh) , palladium(Pd) platinum(Pt) and copper(Cu). In addition to transition metals, this period includes several metalloids that have properties intermediate between those of typical metals and nonmetals . These include boron(B ), siliconSi ) germaniuGe ) arsenicAs ) antimonySb ) tellurideTe ). Most of these metalloids form compounds exhibiting a -3 or -4 oxidation state . Copper is found free in nature as native copper metallic Cu ) but most of its compounds exhibit a +2 or +3 oxidation state . It readily forms alloys such as bronze and brass . Platinum group metals do not corrode or tarnish easily making them ideal for use jewelry and coins
The Atomic Structure
The atom is the basic unit of matter and consists of three particles: protons, electrons, and neutrons. The proton is a positively charged particle, the electron is a negatively charged particle, and the neutron has no charge. The number of protons in an element’s nucleus determines that element’s atomic number. Electrons orbit the nucleus in shells. The energy levels of these shells are determined by the amount of energy required to remove an electron from that shell. The first shell can hold up to two electrons, the second shell can hold up to eight electrons, and so on.
Periods 2, 3, and 4 on the periodic table represent elements with different numbers of valence electrons. Valence electrons are those in the outermost orbital shell of an atom and play a role in chemical bonding between atoms. In general, elements in Period 2 will have two valence electrons (elements in Group 1A), elements in Period 3 will have three or four valence electrons (elements in Groups 2A-2B), and elements in Period 4 will have five or six valence electrons (elements in Groups 3A-3B).
Theatomic radiusof an element is determined by the size of its nucleus and how many orbital shells there are between the nucleus and the outermost orbital shell containing valence electrons. As you move left to right across each period on the periodic table, atomic radius decreases because there are more protons packed into smaller spaces within each successive element’s nucleus. Atoms also get smaller when you move down a group because there are more orbital shells between successive rows on the periodic table.”
The Periodic Table and Atomic Structure
The periodic table is a tabular arrangement of the chemical elements, organized on the basis of their atomic numbers, electron configurations, and recurring chemical properties. Elements in the same column (group) have similar chemical behaviors.
Atomic radii decrease from left to right across a period because as you add protons to the nucleus, the electrons are pulled closer in by the increased nuclear charge. However, there is an increasing effective nuclear charge because there are fewer core electrons shielding each successive outermost electron. The net effect is that each successive element has a smaller atomic radius than its predecessor.
From top to bottom within a group, atomic radii increase because as you add electrons to an atom, they go into successively larger orbitals. The first orbital (1s) can hold two electrons, but each subsequent orbital can hold eight electrons. So when you fill up the first orbital with two electrons (hydrogen), adding more electrons will cause them to go into larger and larger orbitals until you get to the last one (8p).
The Properties of the Periodic Table
The periodic table is a chart that shows how the chemical elements are related to one another. The elements are arranged in order of increasing atomic number. The first element, hydrogen, has an atomic number of 1; the second element, helium, has an atomic number of 2; and so on.
The periodic table is divided into groups and periods. Groups are columns of elements with similar properties. Periods are rows of elements with progressively increasing atomic numbers.
There are three major groups on the periodic table: metals, nonmetals, and metalloids. Metals make up the majority of the elements and are found on the left side of the periodic table (with a few exceptions). Nonmetals are found on the right side of the periodic table (again, with a few exceptions). Metalloids occupy positions between metals and nonmetals on the periodic table and have properties that fall somewhere between those two groups.
As you move from left to right across a period, or from top to bottom down a group, properties generally change in a predictable way. For example, as you move from left to right across a period, metallic character generally decreases; as you move down a group, metallic character generally increases. This trend is due to changes in electron configuration as atoms gain or lose electrons through chemical reactions
The Trends in the Periodic Table
From left to right across the periodic table, atomic radius generally decreases. This trend occurs because, as you move from left to right across the periodic table, the effective nuclear charge (the number of protons in the nucleus) increases. Atoms with a higher effective nuclear charge tend to have a smaller atomic radius.
From top to bottom within a group, atomic radius generally increases. This trend occurs because, as you move down a group, the number of shells of electrons around the nucleus increases. Atoms with more electron shells have a larger atomic radius.
The Uses of the Periodic Table
The periodic table is a chart that shows how chemical elements are related to one another. The elements are arranged in order of increasing atomic number. The periodic table can be used to predict the properties of new elements, and to understand the behavior of existing ones.
The first use of the periodic table was to organize the elements by their properties. This allowed chemists to see patterns in the way that elements behaved. For example, they noticed that some elements were more reactive than others, and that certain groups of elements had similar properties.
The second use of the periodic table was to help scientists understand why atoms behave the way they do. In particular, they used it to explain why atoms form molecules, and why molecules have different shapes and sizes.
The third use of the periodic table was to find new elements. By looking at the patterns in the way that existing elements were arranged, scientists were able to predict where new ones would be found. This led to the discovery of many new elements, including uranium and plutonium.
Fourth,the periodic table has been usedto develop new theories about how atoms work. For example, it was usedto develop quantum theoryufffda theory that explains how subatomic particles behaveufffdand quantum mechanicsufffda branch of physics that studies matter on a subatomic level.
Finally,the periodic table is stillused today as a tool for doing research in chemistry and other sciences. It helps scientists predict how new materials will behave, and it provides a framework for understanding complex phenomena such as climate change and photosynthesis.”
Chapter 6 is the final chapter of the book. In this chapter, we will be discussing “Thinking critically.” Reference: chapter 6 chapter assessment thinking critically.
External References-
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