...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 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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...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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...Atom: the smallest particle of an element that has properties of an element Atomic Theory: Greek philosopher DEMOCRITUS * Atoms can’t be broken into smaller pieces * In any one element, all atoms are exactly alike * Atoms of different elements are different * Atoms of 2 or more elements can combine to form compounds * Atoms of each element have a unique mass * The masses of the elements in a compound are always in constant ratio Bohr Theory: Danish physicist NEILS BOHR * Electrons are arranged in definite shells or NRG levels, considerable distance from the nucleus * Electron configuration: how electrons are arranged * # of electrons = the atomic # of atoms Sir James Chadwick: 1932 * Discovered in the nucleus another particle, neutron * Neutron has same weight as the proton * Neutron has no electrical charge * Nucleus is made up of protons and neutrons * # of protons is = to # of electrons, which is the atomic # of atom Atoms & Molecules * Atoms combine & arrange to form different compounds & molecules * Molecule: 2 or more atoms that are joined together chemically to act as a single unit * Chemical Bond: is the force that holds atoms together * Compound: 2 or more different atoms joined together chemically * All compounds are molecules, but not all molecules are compounds Ex: Oxygen gas = O2 is a molecule, not a compound (both atoms are alike) Water= H20 is a molecule &...
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...STUDENT STUDY GUIDE FOR 8TH GRADE CHEMISTRY Welcome to chemistry. Chemistry is the science of matter and its interactions. Everything around you is made of atoms – atoms and their chemical combinations, molecules. Everything you can see, touch, smell, and taste is made up of chemicals. So, the science of chemistry is a very wide ranging science. Parts can concentrate on how interactions of atoms and molecules allow the nerves in your body to conduct electrical signals. Other parts might concentrate on analyzing clues left by a burglar in order to help the police solve a crime. Still, other parts of chemistry might be involved in making new polymers that might be used by the fashion industry to make more colorful and longer wearing fabrics. If you have access to a computer and the internet, there are a number of excellent tutoring sites to help students gain a better understanding of chemistry. One of the better sites for middle school students Is: www.chem4kids.com/ This site is written at middle school level and has a number of on-line tests that you can use to check your understanding of the material. Several other good internet sites are: http://chemistry.about.com/od/chemistry101/Chemistry_101_Introduction_to_Chemistry.html - Chemistry 101 - a collection of articles and on-line help sites in chemistry http://library.thinkquest.org/10429/low/indexl.htm - ChemWeb on line - an introductory chemistry course on line http://library.thinkquest.org/2923/ - Chemistry...
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...Fundamental Particles of Atoms (Historical Point of View) John Dalton (1808) – atomic theory 1. Atoms – small indivisible particles. 2. Atoms – neither created nor destroyed. 3. Atoms – chemical reactions result from combination / separation of atoms. J. J. Thomson (1897) 1. Electrons – negatively-charged particles. 2. Atoms – positively-charged sphere. Ernest Rutherford (1911) 1. Atoms – consists of a positively-charged nucleus with a cloud of electrons surrounding nucleus. 2. Protons – positively-charged particles. Niels Bohr (1913) 1. Electrons – surrounding the nucleus (orbit). James Cadwick (1932) 1. Neutrons – electrically neutral subatomic particles. 2. Neutrons – mass almost the same with a proton. 3. Nucleus of an atom – consists of protons and neutrons. Modern Atomic Model 1. Nucleus of an atom – consists of protons and neutrons. 2. Electrons – moving around the nucleus (orbits / electron shells/ quantum shells) Atoms Atom – smallest particle of an element. Relative atomic mass (Ar) - (an element) average mass of one atom of the element relative to 1/12 times the mass of one atom of carbon-12. = (average mass of one atom of the element) / (1/12 x mass of one atom of C-12) Or = 12 x [(average mass of one atom of the element) / (mass of one atom of C-12)] Cations – positively-charge ions. Example: H+, K+, NH4+ and Mg2+ Anions – negatively-charge ions. Example: Br-, OH-, O2- and S2O32- Molecule – a group of two or more...
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...detail in Chapter 11. We will also examine intermolecular forces in detail in Chapter 11. Here we will apply what you have learned about atomic structure (Chapter 6), electron configurations, and periodic trends (Chapter 7) to the chemical bonds formed between atoms and ions and the shapes of molecules and ions that contain covalent bonds. • 8-1 Biology: Molecular shape of enzymes specifically allow only certain reactions to occur. Drugs are developed that specifically fit into active sites in the enzyme to affect or even stop its action. Chapter 8 8.1 Interactions Between Particles: Coulomb’s Law 8.2 Covalent Bonding Basics 8.3 Lewis Structures 8.4 Bond Properties 8.5 Electron Distribution in Molecules 8.6 Valence-Shell Electron-Pair Repulsion Theory and Molecular Shape 8.7 Molecular Polarity Chapter Goals • Apply Coulomb’s Law. • Understand forces involved in covalent bonding. • Write Lewis symbols and Lewis structures. • Predict bond properties. • Understand charge distribution in molecules. • Use VSEPR theory. • Identify polar and nopolar species. Chapter 8 Covalent Bonding and Molecular Structure 8-2 8.1 Interactions Between Particles: Coulomb’s Law OWL Opening Exploration 8.1 Coulomb’s Law Matter is made up of atoms and ions that experience both attractive and repulsive forces. The strength of the force holding oppositely charged particles together in any material is described by Coulomb’s Law (equation 8.1). According to this law, force of attraction or repulsion between...
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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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...Multiple-Choice Questions 1) About 25 of the 92 natural elements are known to be essential to life. Which four of these 25 elements make up approximately 96% of living matter? A) carbon, sodium, chlorine, nitrogen B) carbon, sulfur, phosphorus, hydrogen C) oxygen, hydrogen, calcium, sodium D) carbon, hydrogen, nitrogen, oxygen E) carbon, oxygen, sulfur, calcium Answer: D Topic: Concept 2.1 Skill: Knowledge/Comprehension 2) Trace elements are those required by an organism in only minute quantities. Which of the following is a trace element that is required by humans and other vertebrates? A) nitrogen B) calcium C) iodine D) sodium E) phosphorus Answer: C Topic: Concept 2.1 Skill: Knowledge/Comprehension 3) Three or four of the following statements are true and correct. Which one, if any, is false? If all the statements are true, choose answer E. A) Carbon, hydrogen, oxygen, and nitrogen make up approximately 96% of living matter. B) The trace element iodine is required only in very small quantities by vertebrates. C) Virtually all organisms require the same elements in the same quantities. D) Iron is an example of an element needed by all organisms. E) All of the other statements are true and correct. Answer: C Topic: Concept 2.1 Skill: Knowledge/Comprehension 4) Which of the following statements is false? A) Atoms of the various elements differ in their number of subatomic particles. B) All atoms of a particular element have the same number of protons in their nuclei...
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...best answers the question. ______ 1. An ionic bond results from electrical attraction between a. cations and anions. b. atoms. c. dipoles. d. orbital. ______ 2. A nonpolar covalent bond is unlikely when two atoms of different elements join because the atoms are likely to differ in a. density. b. state of matter. c. electronegativity. d. polarity. ______ 3. Bond length is the distance between two bonded atoms at a. their minimum potential energy. b. their maximum kinetic energy. c. their maximum potential energy. d. one-half the diameter of the electron cloud. ______ 4. To draw a Lewis structure, it is not necessary to know a. which atoms are in the molecule. b. bond energies. c. the number of valence electrons for each atom. d. the number of atoms in the molecule. ______ 5. For multiple covalent bonds to form in molecules, the molecules must contain carbon, nitrogen, or a. chlorine. b. hydrogen. c. oxygen. d. helium. ______ 6. The principle that states that atoms tend to form compounds in which each atom has eight electrons in its highest occupied energy level is called the a. rule of eights. b. configuration rule. c. Avogadro principle. d. octet rule. Copyright © by Holt, Rinehart and Winston. All rights reserved. Modern Chemistry 51 Chapter Test Back Print Name Class Date Chapter Test B, continued ______ 7. An example of a molecule that cannot be represented adequately by a single Lewis structure is a. O2. b. CO2. c. O3. d. N2. ______ 8. Lattice energy...
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...Chapter 5: Properties of Matter Matter is anything that has a mass and takes up space. The particle theory of matter is a theory that describes the composition and behavior. Matter can be many up of many different particles or only one. A pure substance is a type of matter that consists of only one type of particle. Then there are mixtures that are made up of at least two different types of particles. There are two different types of mixtures; mechanical mixtures and solutions. A mechanical mixture is a mixture in which the substances in it are distinguishable from each other, either with the unaided eye or a microscope. A solution looks like a pure substance but it contains more than one type of particle. Alloys are when two or more metals are mixed together. A physical property is a characteristic of a substance that can be determined without changing the composition of that substance. A qualitative physical property is not measured and includes hardness, malleability and electrical conductivity. Quantitative physical properties are measured and include temperature, height and mass. A physical change is a change is which the composition of the substance remains unaltered and no new substances are produced Examples of physical change are a change of size or shape, a change of state, and dissolving. A chemical property is a property of a substance that describes its ability to undergo changes to its composition to produce one or more new substances. A chemical; change is a...
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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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...are composed of atoms rather we can see them or not. Some elements are bonded with a variety of atoms to help form the molecules. All matter is made up of atoms that are very small, so small that they human eye cannot see. It does not matter if the liquid, solid, or gas even if it is a mixture or pure. These basic elements are the same elements that make up what is known as the periodic table. Mendeleev Demetri Mendeleev created the periodic table and was trying to put the elements in order by the weight that he saw. As the weights grew from time to time the attributes of one element may be similar to those Mendeleev listed. So Mendeleev would put the elements in a column that were alike chemically (Tro, 2009). All chemicals in the vertical rows of the periodic table were considered to be family because the attributes were a lot alike. In group 1A of the table of elements are the alkali metals, in column 7A are the halogens (Tro, 2009). Noble gases are in the column of 8A, the noble gases are in this specific column because they are gases that are unreactive because the shell has being closed. So because of similarities Mendeleev built has table of elements based on similarities. Atoms Atoms are considered the smallest existence that has similar attributes of an element, but the atom cannot be broken down into a smaller part. The formation of molecules happens when two or more atoms are put together, which can happen in many different ways. When two atoms of oxygen are put...
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