Science 5.1 Atomic number The number of protons in an atom is known as the atomic number. Atomic number = number of protons. Each element has a characteristic and identifying atomic number. Proton number equals atomic number. The mass number minus the atomic number is the neutrons, the atomic number is the neutron. Electrons and protons are equal and are the same number. Atoms Atoms are particles that make up all the substances in the universe. Element The number of protons in the nucleus determines what element the atom belongs to. There is 118 different elements, 26 of these are not naturally found on earth but are synthetic, having been made in the laboratory. Isotopes Isotopes - elements with the same number of protons but with different number of neutrons. This means that isotopes are atoms of the same element, isotopes have different atomic masses, isotopes have different number of neutrons in the nuclei. Mass number The mass number of an atom is the total number of protons and neutrons. Mass number = number of protons + number of neutrons. Nucleus The nucleus is at the center of each atom is its nucleus, a tight, dense bundle of protons and neutrons. Neutrons are slightly heavier than protons and both are roughly 1800 times heavier than electrons. For this reason, almost all of an atom’s mass is in its nucleus. Protons carry a positive charge while neutrons are neutral, having no charge. The positive charges of all those protons in the nucleus give the nucleus a positive charge too and electrons are negative. Protons have a positive charge, electrons have a negative charge and neutrons have a neutral charge. Homework chapter 5, q1 3 4 7 9 14 8 The periodic table is a list of all known of all known elements. 2,8,1 sodium 2,8,2 magnesium 2,8,3 aluminum 2,8,8,2 calcium 2,1 lithium 2,8,1 sodium 2,8,8,1 potassium 1a period 4 1b period 5 2a 2,8,4 2b 2 2c 2,5 2d 2,8,2 Three major groups of elements found on the periodic table. Metals are located to the left of the zigzag line. Nonmetals are located to the right of the zig zag line. Metalloids can be found clustered around the dark zig zag line that separates metals and nonmetal. Physical properties of metals. Have luster-shiny, are conductors and electricity and heat can move through them easily. Malleable- can be hammered into a different shape. Ductile-can be drawn into a wire. High density – heavy for their size. Metals are solid, except for mercury. Transition elements (group 1 to 3) are all metals and include many of our most useful colourful and valuable ones such as iron, copper, zinc, gold and silver. Their salts and solutions are also colorful. The transition metals have very similar properties. For example, they all tend to be relatively hard with high melting points. Physical properties of nonmetals. Dull not shiny. Nonconductors – heat and electricity do not move through them easily. Brittle – breaks easily. Most nonmetals are gases at room temperature. Properties of metalloids. Metalloids have properties of both metals and nonmetals. Metalloids are solids that can be shiny or dull. They can conduct electricity and heat better than nonmetals but not as well as metals. Metalloids are malleable and ductile. Alkali metals are lithium, sodium, potassium, rubidium, cesium, francium. All the alkali metals form +1 ions are far too reactive to be found naturally in their pure form. Have typical metallic properties. Display similar extreme chemical behavior. Metal atoms have a weak hold on their outer shell electrons. As you move down a group, extra shells are added and so this hold gets even weaker. This makes metal more unstable and more reactive. Lithium atoms are the smallest in group 1 and lithium metals fizzes when put in water. Sodium atoms are all little, bigger and can react explosively with moisture in the air. Reactions with moisture become even more violent as you move up. As we move down the group the reactivity of alkali and alkaline earth metals increases because the size of the atom gets bigger, and it is easy to remove valence electrons. The element group 14 display a large range of properties. The group begins with the nonmetal carbons, moves through metalloid silicon and germanium, and finishes with the metallic element tin and lead. Elements in group 14 have 4 electrons in their outer shell which they can use to join or bond with other elements. The first element in group 14 is carbon. Carbon exists as an element in several forms (allotropes) such as charcoal, diamond, and graphite. The second element in group 14 is the metalloid silicon, an abundant element contained in sand. Sand contains ground up particles of minerals such as quartz, which is composed of silicon and oxygen. Silicon is a major component of glass. The third element, germanium is used in fluorescent lights and its oxides are used in the production of lenses for optical instruments such as microscopes. Both silicon and germanium are semiconductors and are widely used in electronic components. a semiconductor does not conduct electricity as well as metals but does conduct better than nonmetals. The fourth and fifth in group 14, tin and lead are the two heaviest elements in group 14 and are both metals. Tin and lead are metals and have characteristic metallic properties. The group 17 elements are known as the halogens, fluorine, chlorine, bromine, iodine, astatine. All the elements are in group 14. Atoms of halogens, forms ions with a charge of -1. They are not found in nature in their pure form but are found in various types of salts, and it gets bigger and become less reactive as you move down the group. The halogen fluorine is the most reactive of the halogens. Chlorine is less reactive than fluorine. Bromine is les reactive than chlorine. Iodine is the least reactive of the four nonmetals. Halogens will react with sodium to form an ionic compound with the formula NaX, where X is any halogen. Halogens will react with carbon to form a covalent compound with the formula CX4, where X is any halogen. the noble gases of group are colorless gases that naturally occur in the atmosphere. Each noble gas produces a unique color when heated, helium glows yellow, neon glows red-orange, and argon produces a bluish-violet color. Aluminum 2 Boron 2 Sodium 2 Homework Chapter 5.4 question 1-19 Pearson chapter 5 review question 1-21 Chapter 5.4 Questions 1- 19 1a, The electron shell is where the electrons spin around the nucleus. 1b, The electron configuration is the distribution of electrons of an atom or molecule in atomic or molecular orbitals. 1c, Fluoresce absorbs UV light and re-emit it as a blue light. 2a, ground state 2b, Excited electrons 3, 20 sometimes 26 4, Period 4 elements have electrons in the first four electron shells. All period 4 elements have one or more electrons in the fourth electron shell (valence electrons). When atomic number increases by one, another electron is added. 5a, 2 electrons 5b,8 electrons 5c, 8 electrons 5d, 8 electrons 6, 18 electrons 7a, positive 1 7b, positive 2 8, elements are placed in order on the periodic table based on their atomic number, how many prtons they have. 10a, it is because of its completely filled outer shell which gives it noble gas properties(i.e. it doesn’t form compounds). You might say that it should be in group 2 because of 2(1s) electrons but since it has noble gas properties it is placed along with them in group 18. 10b, They don't need to react or join up with other elements to form compounds, nor do they want to give up their electrons, so helium and other noble gases like neon and argon tend to float around by themselves. The noble gases are located in the far right column of the periodic table of elements – in group (column). 11, the elements in each groups have the same number of valence electrons. 12, As we go down the group, the atom gets bigger. The bigger the atom, the further away the last electron. Therefore, the attraction between the nucleus and the last electron gets weaker. This makes it easier for the atom to give up the electron which increases its reactivity. 13, it will be in the 2nd electron shell. 14a, lithium (with 3 electrons) 14b, carbon (with 6 electrons ) 14c, sodium (with 11 electrons) 14d, chlorine (with 17 electrons) 16a, 2,3 16b, 2,8,7 16c, 2,8,8,2 16d, 2,8,18,6 16e, 2,8,18, 8, 2 17, they all have positive ion charges. 18a, silicon 18b, helium 18c, nitrogen 18d, magnesium 19a, period 2, group 16 19b,period 3, group 18 Chapter 5 review questions. 1a, The definition of element is In chemistry, refers to a simple substance that cannot be broken down into smaller parts or changed into another substance. The basic part of an element is an atom, which contains protons, neutrons, and electrons. All atoms of an element have the same number of protons. 1b, the definition of atomic number the number of protons in the nucleus of an atom, which is characteristic of a chemical element and determines its place in the periodic table. 1c, the definition of allotrope one of two or more existing forms of an element: Graphite and diamond are allotropes of carbon. 1d, the definition of organic molecule organic compound is any chemical compound that contain carbonhydrogen or carbon-carbon bonds. 2, 118 elements 3, The elements are helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), radon (Rn), and oganesson (Og ). 4a, group 7 4b, group 2 4c, group 8 4d, group 1 5, inert gases 6a, (F) fluorine 6b, (Ca) calcium 6c, (Na) sodium 6d, (Pb) lead 8, Atoms of the same element that contain the same number of protons, but different numbers of neutrons, are known as isotopes. Isotopes of any given element all contain the same number of protons, so they have the same atomic number (for example, the atomic number of helium is always 2). 9a, Mercury 9b, The third period contains eight elements: sodium, magnesium, aluminium, silicon, phosphorus, sulfur, chlorine and argon. The first two, sodium and magnesium, are members of the s-block of the periodic table, while the others are members of the p-block. 9c, tin and lead 10a, Silicon 10b, germanium 10c, Tin 10d, Lead 11a, phosphorus 11b, carbon 11c, Chlorine. 12a, bromine 12b iodine 13 Protons and neutrons are in the nucleus and electrons are in the electron shell outside of the nucleus which creates an atom. 14 atomic number is the proton and mass number is the neutrons 15, they all have different ionic compounds. 16 one of it is carbon and the other is silicon. 17, subatomic particles are a minute portion of matter There is no question 18. 19a, I answered all the questions finely. 19b, I understood the assessment material, 20, the answer is 23. Alkali metals ware if they react with water, they produce base solution and hydrogen. A chemical reaction cannot be seen; It occurs on the submicroscopic level. A chemical equation is a written expression that illustrates what happens during a chemical reaction. All chemical equations have three basic parts. Reactants arrow products. All alkali metal ware if they react with water and different types of liquids, the alkali metals produce a base solution and also make hydrogen. A chemical reaction cannot be seen Chemical equations Copper oxide reacts with sulfuric acid to make copper sulfate and water. Zinc and hydrochloric acid react to make zinc chloride and hydrogen. Magnesium and chlorine react to make magnesium chloride. Copper and silver nitrate reacts to make copper nitrate and silver. Copper carbonate and sulfuric acid react to make copper sulfate, carbon dioxide and water. Juan burns different masses of magnesium metal with oxygen to form magnesium oxide. He measures the mass of reactants and products before and after, as shown in the table. A chemical equation are one of the most basic tools that scientists use to describe what’s happening during a chemical reaction. A chemical equation can communicate detailed information about any chemical reaction in a single line.
