...Atoms are the smallest entities which resemble the properties of an element and cannot be broken down into smaller parts. Molecules are formed when two or more atoms are combined. This formation can happen in a variety of ways. When two oxygen atoms join O2 is formed, and when three oxygen atoms join O3 or ozone is formed. Both of these have different properties. Different atoms can also combine to form molecules. Hydrogen combines with sulfur to form H2S and hydrogen and oxygen also combine to form H2O. Dmitri Mendeleev’s Periodic table is based on atomic weight, whereas, the modern periodic table keeps the atomic number as the base. An atomic table arranges elements from left to right in a row with the atomic number and properties gradually changing. The elements on the next row will actually exhibit similar properties as the ones above or below it. This provides an example of the periodicity nature of the elements. The columns of different elements in a period have the same or very similar properties. The properties of the elements change gradually as the columns move down through the periodic table. Atoms in similar families, such as H2S and H2O, exhibit both similar properties and molecular structure. This shows periodicity in both the molecules and the individual atoms. Alkali metals contain a single electron in their outer shell rendering them highly reactive. This allows them to be ready to donate this single electron to form molecules with substances...
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...Atoms, Molecules, and Elements Michelle Faunce-Carroll CHM/110 - INTRODUCTORY CHEMISTRY BSDT1HX1M4 WILLIAM DE VORICK AUGUST 10, 2015 Atoms, Molecules, and Elements Atoms, Molecules, and Elements are a part of everything we do in life. Most people don’t recognize the extent that chemistry plays in our everyday lives. From the foods we eat, to the products we use for cleaning ourselves, our homes, our cars; atoms, molecules, and elements are a part of all of these things. Dmitri Mendeleev began studying elements in the early 1800’s. Through his learnings he found that elements are sortable, have similar properties, and are even predictable. In addition to this his research also led to his coming up with the periodic table. Thanks to Dmitri Mendeleev we can now know the way molecules are formed. Because of this we know the charge of the elements, which in turn helps us to know how they will react with each other when combined, we are able to predict if this will be a good or bad reaction. Grouping elements into families was first taught by Dmitri Mendeleev. He began by studying their atomic weight, charge, and reactivity. And then grouping the elements with similar properties within the same family. Within these families we can look at how they would react with other elements on the periodic table. Take hydrogen for example when this is paired with oxygen to form H2O, you have to have 2 hydrogen...
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...Atoms, Molecules, and Elements Atoms, Molecules, and Elements Take a look out the window. Consider that everything that you can and cannot see is composed of atoms. Some of these may be bonded with other atoms to form molecules. All matter is composed of atoms that are too small to see. Weather the matter is liquid, gas or solid, pure or a mixture. It is the basis for elements that make up what we know today as our periodic table. Demetri Mendeleev was trying to organize the elements into a table by weight when he noticed that as the weights increase occasionally the properties of one element would resemble those of an element he already listed so he placed these elements in a column under the ones they resembled chemically ( Capri, PhD, 2003). Each chemical in the vertical rows on the periodic table are considered families or groups because they have properties that are similar to each other. All the chemicals in group 1A of the periodic table are considered alkali metals. Alkali metals are similar in that each of them has only one atom in the outermost shell and they are very reactive when combined with other elements. All elements in column 7A are halogens. Halogens are also highly reactive oxidizing agents that are called “salts”. All halogens have 7 electrons in their outer shells, giving them an oxidation number of -1 ( Bodner Research Web, n.d.). Noble gases can be found in Column 8A. These elements are all considered to belong in this column because they are all...
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...Atoms, Molecules, and Elements Paper Candace Jefferson March 8, 2016 Charles Chau Chem/110 Atoms are the smallest particles and have the resemblance properties of an element they cannot be broken down and this is considered the building blocks. The atom has a nucleus that is surrounded by electrons. An atom can be negatively or positively charged just depends on the surrounding particles. Molecules are formed when there is a group that is formed and then they are bonded together. It will all depend on how they are bonded that will determine the type of element that will be formed. The periodic table was created by a Russian chemist by the name of Dimitri Mendeleev. He created this table so that everyone would be able to see all of the things that he is able to see. This table is used all through the school system helping people all over the world understand chemistry and making it a lot easier. He wanted it to be organized in a way so that it will be in a group separating certain characteristics. The main purpose of the periodic table was to show the chemical properties explaining the similarities and the differences between everything that he would have on the periodic table. “Mendeleev...
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...Atoms, Molecules, and Elements Paper Carolyn R. Slaughter CHM/109 October 12, 2014 Jodi Wolf Atoms, Molecules, and Element Paper Each column within a periodic table is called a family or group of elements. The Group 1A elements are called alkali metals and they are all reactive metals. The Group 7A elements called halogens are very reactive nonmetals. The Group 8A elements are called noble gases. The noble gases are inert (or unreactive) compared to other elements. Alkali metals and halogens are both reactive. They react spontaneously with water, oxygen and other elements. The elements form a strong base s that is capable of neutralizing strong acid and then reacting. Halogens and alkali have high electro negativities and a large number of valence electrons. These two elements display physical properties which makes them highly reactive when combined together. Noble gases are chemically stable and will not combine with other elements to form compounds (Tro, 2009). When comparing properties of molecules formed from atoms in similar families such as H2S and H2O, there is a similarity of properties in the elements. Both display similar molecular makeup and properties. First they both have been composed of two hydrogen atoms. H2S is a gas formed from 2 hydrogens, water, and sulfate. H2O remains liquid because of its electronegativity it is 2 hydrogens and oxygen, which is water. The trends and patterns of the periodic table were organized by Mendeleev. All elements in...
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...The Shapes of Molecules Introduction Whether we consider the details of simple reactions, the properties of synthetic material, or the intricate life-sustaining processes of living cells, molecular shape is a crucial factor. 10.1 Depicting Molecules and Ions with Lewis Structures Lewis structures, also called electron-dot structures or electron-dot diagrams, are diagrams that show the bonding between atoms of a molecule, and the lone pairs of electrons that may exist in the molecule. A Lewis structure can be drawn for any covalently-bonded molecule, as well as coordination compounds. Using the Octet Rule to Write Lewis Structures The octet rule tells us that all atoms want eight valence electrons (except for hydrogen, which wants only two), so they can be like the nearest noble gas. Use the octet rule to figure out how many electrons each atom in the molecule should have, and add them up. The only weird element is boron - it wants six electrons. Lewis Structures for Molecules with Single Bonds The atoms share a pair of electrons, and that pair is referred to as a bonding pair. The pairs of electrons which do not participate in the bond have traditionally been called "lone pairs". A single bond can be represented by the two dots of the bonding pair, or by a single line which represents that pair. The single line representation for a bond is commonly used in drawing Lewis structures for molecules. · Hydrogen atoms form one bond. · Carbon atoms four bonds. ...
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... Linus Pauling suggested that carbon is able to create four unpaired orbitals by promoting one electron from the 2s orbital to the empty 2pz orbital. This hybridizes the one 2s and three 2p orbitals together. This configuration is called ‘sp3’. Like s and p orbitals, the ‘shape’ of sp3 orbitals can be defined by a probability density map of electron location around the nucleus. The shape of a sp3 orbital looks like this: Since carbon is able to form 4 hybridized orbitals, they form a geometric arrangement called tetrahedral. 1 2 s sp3 1 2 s sp3 In terms of energy, the resulting hybridized orbitals are in between the energy of the s and p subshells. Overall this is a higher energy state than if the atom were unhybridized, therefore atoms are only found in a hybridized state when they are bonded, never on...
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...What is a molecule? Well, simply put it's just a group of atoms bonded together. However, there are special molecules; these are polar and nonpolar molecules. Molecules make us up, they are made up of atoms. Which have electrons, electrons are little balls with a negative charge, and like magnets opposite attract. This brings us to electronegativity. Electronegativity is a measure of the tendency towards an atom to attract a bonding pair of electrons. What is a polar molecule? Simply put, it's a particle that has two or more covalently bonded atoms. (A covalent bond is a bond where two atoms share their electrons to become stable ) With an asymmetric distribution of changes, this occurs to molecules that are asymmetric along at least one axis....
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...Biological Molecules End of this chapter the student will learn about: a) What is the Functional groups and types. b) Macromolecules a) The build up of covalent bond by condensation or dehydration. b) The brake up of covalent bond by hydrolysis c) The chemical elements of life: a review Functional groups contribute to the molecular diversity of life • The components of organic molecules that are most commonly involved in chemical reactions are known as functional groups. • Functional groups are attachments that replace one or more hydrogen atoms to the carbon skeleton of the hydrocarbon. • Each functional groups behaves consistently from one organic molecule to another. • The number and arrangement of functional groups help give each molecule its unique properties. • The basic structure of testosterone (male hormone) and estradiol (female hormone) is identical. • Both are steroids with four fused carbon rings, but they differ in the functional groups attached to the rings. • These then interact with different targets in the body. Fig. 4.8 • There are six functional groups that are most important to the chemistry of life: hydroxyl, carbonyl, carboxyl, amino, sulfhydryl, and phosphate groups. • All are hydrophilic and increase solubility of organic compounds in water. Functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules. • Hydroxyl...
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...formal charge • Chemical bond the force of attraction that binds atoms together in a chemical compound • When atoms react to form chemical bonds, only the electrons in the outermost / valence shell are involved 3 Forms of Chemical Bonds 1) ________molecular bond – forces hold the atoms within a molecule • Ionic / Electrovalent Bond • Covalent Bond • Metallic Bond 2) ________molecular bond – forces between the molecules • Hydrogen bonding • Van der Waals 3) Co-ordinate / Dative Bond 5 FHSC1114 Physical Chemistry 4 Electrons In An Atom 2 groups of electrons: a) Valence electrons • ____________ shell electrons • similar chemical properties • similar group number in periodic table b) Core electrons • ________ shell electrons • not involved in chemical behaviour 6 1 Centre for Foundation Studies, UTAR Valence & Core Electrons Bond & Lone Pairs Electrons • Valence electrons are distributed as shared (bond pairs) & unshared (lone pairs) B (1s22s22p1) Core e- = [He] Valence e- = 2s22p1 Cl H Br ([Ar]3d104s24p5) lone pair e- Shared or bond pair e- Core e- = [Ar]3d10 Valence e- = 4s24p5 7 Lewis Symbol & Lewis Structures This is called a LEWIS ELECTRON DOT structure (Lewis Structure) 8 Building A Lewis Electron Dot Structure • Lewis symbol — a chemical symbol to represent the nucleus & core electrons of an atom, together with dots placed around the...
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...ATOMS AND MOLECULES - The properties of matter depend on the properties of atoms and molecules from which it is made. Laws of chemical combination (I.) Law of conservation of mass: It states that mass can neither be Created nor destroyed in a chemical reaction. - It means that in a chemical reaction, the total mass of products is equal to the total mass of reactants. There is no change in mass during a chemical reaction. (ii) Law of constant proportions: In a chemical substance the elements are always present in definite proportions by mass. - Dalton’s atomic theory - The postulates of his theory are as follows: (I.) All matter, whether an element, a compound, or a mixture is Composed of very tiny particles called atoms. (ii.) Atoms are indivisible particles, which cannot be created or Destroyed in a chemical reaction. (iii.) Atoms of a given element are identical in mass and chemical Properties. (iv.) Atoms of different elements have different masses and chemical Properties. (v.) Atoms combine in the ratio of small whole numbers to form compounds. (vi.) The relative number and kinds of atoms are constant in a given compound. - Drawbacks of Dalton’s atomic theory: (I.) Atoms were indivisible according to Dalton. We now know that under special circumstances, atoms can be further divided into still smaller particles called electrons, protons and neutrons...
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...covalent bonds. Use each of the terms below just once to complete the passage. covalent bond molecule sigma bond exothermic pi bond When sharing of electrons occurs, the attachment between atoms that results is called a(n) (1) . When such an attachment is formed, bond dissociation energy is released, and the process is (2) . When two or more atoms bond by means of electron sharing, the resulting particle is called a(n) (3) . If the electrons shared are centered between the two atoms, the attachment is called a(n) (4) . If the sharing involves the overlap of parallel orbitals, the attachment is called a(n) (5) . In your textbook, read about single and multiple bonds and bond strength. Circle the letter of the choice that best completes the statement or answers the question. 6. In what form do elements such as hydrogen, nitrogen, and oxygen normally occur? a. as single atoms c. as molecules containing three atoms b. as molecules containing two atoms d. as molecules containing four atoms 7. How many electrons are shared in a double covalent bond? c. none b. one c. two d. four 8. Bond length is the distance between d. two molecules of the same substance. c. the nuclei of two attached atoms. e. the electrons in two attached atoms. d. the orbitals of two attached atoms. 9. Which of the following relationships relating to bond length is generally correct? ...
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...Centre for Foundation Studies, UTAR CHAPTER 2 Chemical Bonding Chapter Scopes Bond energies, bond lengths & bond polarities Drawing Lewis structure and calculate the formal charge Forms of Chemical Bonds 1) Intramolecular bond – forces hold the atoms _______ a molecule • Ionic / Electrovalent Bond • Covalent Bond • Metallic Bond 2) Intermolecular bond – forces ________ the molecules • Hydrogen bonding • Van der Waals 3) Co-ordinate / Dative Bond FHSC1114 Physical Chemistry Chapter Scopes • • • • Electrovalent / ionic bonding Covalent bonding Co-ordinate / dative covalent bonding Intermolecular bonding (including hydrogen bonding, Van der Waals) • Metallic bonding • Electronegativity Chemical Bond • Chemical bond − the force of attraction that binds atoms together in a chemical compound • When atoms react to form chemical bonds, only the electrons in the ______ ___________ are involved Electrons In An Atom 2 groups of electrons: a) Valence electrons • outermost shell electrons • chemical properties • = group number in periodic table b) Core electrons • inner shell electrons • not involved in chemical behaviour 1 Centre for Foundation Studies, UTAR Valence & Core Electrons B (1s22s22p1) Core e- = [He] Bond & Lone Pairs Electrons • Valence electrons are distributed as shared (bond pairs) & unshared (lone pairs) Valence e- = 2s22p1 Core e- = [Ar]3d10 Valence e- = 4s24p5 Lewis Symbol & Lewis...
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...64 Practice Problems – Chapter 14 – Chem 1C 1. Which of the following molecules contains a nitrogen atom that is sp2 hybridized? A) NH3 B) NO3- C) N2 D) HCN E) C2N2 2. Consider the structure of glycine, the simplest amino acid: What is the total number of bonds in the molecule? A) 0 B) 1/2 C) 1 D) 2 E) More information is needed. 3. What is the hybridization of I in the molecule ICl3? A) sp B) sp2 C) sp3 D) dsp3 E) d2sp3 4. What is the hybridization of S in the molecule H2S? A) sp B) sp2 C) sp3 D) dsp3 E) d2sp3 5. What is the hybridization of C in the ion CN-? A) sp B) sp2 C) sp3 D) dsp3 E) d2sp3 6. Atoms that are sp3 hybridized form ____ pi bond(s). A) 0 B) 1 C) 2 D) 3 E) 4 7. What is the hybridization of the central atom in SF6? A) sp B) sp2 C) sp3 D) dsp3 E) d2sp3 8. What is the hybridization of the central atom in PCl4+? A) sp B) sp2 C) sp3 D) dsp3 E) d2sp3 9. What is the hybridization of the central atom in IF5? A) sp B) sp2 C) sp3 D) dsp3 E) d2sp3 10. What is the hybridization of the central atom in SF4? A) sp B) sp2 C) sp3 D) dsp3 E) d2sp3 11. What is the hybridization of O in OF2? A) sp B) sp2 C) sp3 D) dsp3 E) d2sp3 12. Consider the following molecule. (Lone pairs are not drawn in.) Specify the hybridization of each carbon atom (in numeric order: C-1 C-2 C-3 C-4 C-5). A) sp2 sp2 sp2 sp3 sp B) sp2 sp2 sp2 sp3 sp3 ...
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...Introductory Chemistry Introduction Instructor: Dr. Tao Tao Course Section: CHEM1405.6013-6014 Meeting Time: TTh 6:00pm-9:10pm Bldg 13-629 Office Hours: TTh 5:30 pm-6:00 pm Contact: tao.tao@lonestar.edu Introductory Chemistry 2 Course Material Requirements • Textbook – Introductory Chemistry, by Nivaldo J. Tro 5th edition • Chapters 1-4, 6-10, 14 • Sections, 5.6-5.10, 12.4-12.8, 13.6-13.8 • Scientific Non-programmable Calculator • Safety Goggles for Lab • Lab Coat/Apron (Optional) Introductory Chemistry 3 Evaluation and Grade • Tests: 45%; 4 tests, best of 3, no make-up unless good excuses (documented, in advance notice) • Open-book Quizzes: 10%; best n-2, no make-up • Laboratory: 25% • Final Exam: 20% • Homework: Encouraged but not mandatory • Problem Set: Provides but not mandatory • Final withdrawal day: Nov. 10th, 2014 Introductory Chemistry 4 Lab Report/Grade Guideline • Pre-lab write-up (30%): Complete before lab starts, will be checked and signed for completeness – – – – Title/Date Aim/Purpose Introduction Procedures • Lab Performance and Quality of data (25%): will be checked and signed when leaving lab – Observations – Collect and record data • Post-lab (40%) – Result (Calculations, Graphs, Interpretations etc), – Discussions/Conclusions – Post-lab questions if any • Overall Report Neatness (5%) • Report due one week after the completion of experiment for full credit; after two weeks, no report will be accepted, and no credit...
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