Lesson 1 Using the Periodic Table Dimitri Mendelev

Lesson 1 - Using the Periodic Table Dimitri Mendelev knew that some elements were very similar, and it made sense to him to group them together. For example, he grouped together sodium, lithium and other metals that reacted violently with water. In 1886, the element Germanium was discovered. This element had the exact properties of a missing element on Mendeleev’s table. Henry Mosley rearranged the elements to the table we have now based on the atomic number of the elements.

Alkaline Earth Metals Alkali Metals Halogens Nobel Gases TRANSITIONAL METALS

Period Horizontal row of elements in the periodic table They are numbered from 1 to 7. The most reactive metals start on the left, as you move right the metals become less reactive. Group/Family Vertical column of elements in the periodic table They are numbered from 1 to 18 Elements in the same group have similar reactivity.

Element Symbol & Name Element symbols are used to describe elements because they are the same in every language and it will make communication easier. An element symbol consists of 1 or 2 letters. The first letter is capitalized, and if there is a second letter it is lowercase. The rule about capitalization is very important. Ex. The symbol Co stands for cobalt, while CO represents Carbon Monoxide (a compound that contains both Carbon and Oxygen) The symbol is sometimes an abbreviation of the elements English name, other times it abbreviates the Latin name. Ex/ the symbol for Silicone is Si where as the symbol for Silver is Ag because its Latin name is Agentanium. Some elements are named based on where they were discovered, like californium which was discovered at the University of California. Titanium is a strong yet light metal element. It is named for the Titans, powerful gods of Greek mythology.

Atomic Number The atomic number is typically found in the top left corner of each element square. It shows how many protons are in one atom of that element. Atoms have a neutral charge, therefore the number of electrons equals the number of protons. As you move across the periodic table from left to right the atomic number increases by one. Ex/ Nickel’s atomic number is 28, therefore it has 28 protons and 28 electrons

Atomic Mass Typically found under the elements name in each element square. Atomic mass is always expressed as a decimal, because each element, except for Fluorine, can form isotopes, which are atoms with different numbers of neutrons in them and therefore different masses. Atomic mass is the average mass of all an element’s different isotopes. Mass is measured in Atomic Mass Units (amu). Hydrogen has an atomic mass of 1. 01 amu and iron has an atomic mass of 55. 85 amu. This means that iron is 55 times heavier than hydrogen atoms.

Mass Number The mass number of an element is the atomic mass rounded to a whole number. It is the total number of protons and neutrons in an atom. Electrons are too small, therefore they have very little effect on the total mass of the atom. To determine the number of neutrons an element has subtract the atomic number or protons from the mass number (ROUNDED!) MASS NUMBER – ATOMIC NUMBER = NEUTRONS (OR PROTONS)

Isotopes A form of an atom that has a different number of neutrons than the common form of that atom. Ex. The most common form of hydrogen has 1 proton and 1 electron but 0 neutrons. A small percentage of hydrogen atoms have 1 proton, 1 electron, and 1 neutron. An even smaller percentage of hydrogen atoms have 1 proton, 1 electron and 2 neutrons. The most common form of carbon contains 6 protons and 6 neutrons, therefore has a mass number of 12. Carbon-14 is an isotope of carbon that has a mass number of 14. Because it isn’t the most common form of carbon, its mass number is indicated with “-14” at the end of the element name. Carbon-14 is used for carbon dating.

Ion Charge Ions are formed when atoms or groups of atoms gain or lose electrons. Ion charge is the electric charge that an atom takes on when it loses or gains electrons. Elements that gain electrons become negatively charged, whereas elements that lose electrons become positively charged. Elements with atoms that form similar ions are grouped together in the periodic table. For example, elements in the first column on the left side of the periodic table all form positive ions of ion charge +1.

Element Atomic Name Symbol Number Hydrogen H Bromine 81 1 Br Atomic Mass Number 1. 01 35 1 Ion Charge +1 81 81 -1 # of Protons Electrons Neutrons 1 35 1 0 35 46 Iron Fe 26 55. 85 56 +2, +3 26 26 30 Titanium 46 Ti 22 46 46 +3, +4 22 22 24 Pb 82 207. 21 207 +2, +4 82 125 Lead Uranium – 235 U 92 235 +6, +4 92 92 143 Vanadium V 23 50. 94 51 +5, +4 23 23 28 P 15 30. 97 31 -3 15 16 Ar 18 39. 95 40 n/a 18 18 22 Mg 12 24. 31 24 +2 12 Uranium U 92 238. 03 238 +6, +4 92 146 Carbon C 6 12. 01 12 +4, -4 6 6 Helium He 2 4. 00 4 n/a 2 2 2 Phosphorus Argon Magnesium

Metals, Non-Metals and Metalloids Metals are found of the left side of the periodic table. Physical Properties – Most are shiny and silver/grey. – Excellent conductors of heat and electricity. – They are also malleable and ductile. – Most metals are solid at room temperature. Mercury is a metal that is liquid at room temperature. Chemical Properties – Some metals react explosively with water (Ex. Sodium (Na)) – Others will not react even if mixed with strong acid (Ex. Platinum (Pt))

Non – Metals Only 17 of the known elements are classified by scientists as nonmetals. These elements are not grouped because of their similarities but because they don’t resemble metals. Non-Metals are found of the right side of the periodic table. Physical Properties 11 of the non-metals are gases at room temperature, 5 are solid, and 1 is liquid. Solid non-metals do not conduct heat or electricity. Solid non-metals are brittle and not malleable elements. Solid non-metals have little or no metallic lustre. Chemical Properties Some non-metals are very reactive. Sulfur is a yellow solid. It is a very reactive poisonous gas and will burn in air. It will melt into a liquid with little heat. Pure bromine is very reactive and toxic.

Metalloids Have both metal and non-metal properties. They are often used in electronics, such as computers. Physical Properties Metalloids conduct electricity not very well, they are called semi-conductors. Silicone is the most common metalloid. It is shiny and grey, but unlike a metal, it is brittle. About 40% of the mass of any rock comes from silicon. It is also a major component of glass.

Element Families Alkali Metals Group 1 elements Similarities Silver – grey in colour. Like other metals, they are malleable and ductile; they conduct heat and electricity. Unlike other metals, they have low melting points and melt below 181°C. These are the Alkali metals These metals react when exposed to water or air. Differences From top to bottom, density increases, and reactivity decreases.

Alkaline-Earth Metals Group 2 elements Silvery – white in colour. These elements also react when exposed to water or air, however their reactivity is not as violent as alkali metals. They are harder and have a higher density than sodium and potassium Alkaline-Earth Metals have higher melting points that alkali metals.

Halogens Group 17 elements. Similarities Each has a noticeable but different colour. They all have a low melting points. They are the most reactive non-metals. Differences Moving from top to bottom, the colours of the vapours grow in intensity. Also, melting points increase.

Noble Gases Group 18 elements Similarities All exist naturally colourless gases, but will glow with bright colours if an electric charge is run through them (Neon lights). They are the most stable and unreactive elements. Differences From top to bottom, the density increases.

Classification of Matter Pure Substances - Contain only one type of particle - can exist in three states of matter: solid, liquid and gas Compounds - Examples: water, salt, sugar Elements - Examples: iron, gold, oxygen All Matter Mixtures - contain two or more substances Homogeneous Mixtures (Solutions) - appear to be one substance - particles of different substances are intermingled - examples: vinegar, clear air Heterogeneous Mixtures (mechanical Mixtures) - two ore more parts can be seen - different kinds of particles stay together - examples: soil, blood, concrete

Identify each mixture as homogeneous or heterogeneous. Dirt Heterogeneous Mixture Sterling silver bracelet Homogeneous Mixture Sample of pond water Heterogeneous Mixture Recycled paper Heterogeneous Mixture

Read the descriptions below. In the space provided, indicate whether each mixture is a mechanical mixture (MM) or a solution (S) • The different substances in this mixture can be distinguished from each other with the unaided eye or a magnifying glass MM • The substances in this mixture cannot be separated by filtering S • When this mixture is left to stand undisturbed, the substances do not separate by floating to the top or settling to the bottom. S • This mixture appears cloudy or opaque. You cannot see through it clearly. MM

Combining Metals Some metals, such as tin and gold, are too weak to be used alone for some purposes. Therefore, to make a substance stronger, some metals are often melted and mixed with other melted metal elements. The mixture is cooled to become a solid solution. A solution of two or more metals is called an alloy. Common alloys include a combination of gold and nickel or manganese, this is often called white gold because it has a lighter colour than pure gold. White gold is often used in engagement rings and wedding bands to give them strength and durability. Alloys are used in magnets, sports equipment, vehicles and many other household items.

Types of Compounds Ionic Compounds Properties Ionic compounds have high melting points (they are solid at room temperature). When dissolved in water, they are good conductors. They all form crystals.

How they are formed: Ionic compounds are pure substances formed as a result of the attraction between ions of opposite charges. Metal atoms tend to lose electrons, therefore they become positive ions. Whereas, non-metal atoms tend to gain electrons, therefore they become negative ions. Ex/ When sodium combines with chlorine, an electron from the highest energy level of a sodium atom moves to the outer level of the chlorine atoms. This cause the atoms to become neutral.

Consider the Bohr Model for both Chlorine and Sodium:

Molecular Compounds Composed of 2 non-metals. May be solid, liquid or gas at room temperature. Tend to be insulators or poor conductors of electricity (because there is no charge associated with their creation). They have relatively low melting and boiling points due to the weak forces between molecules. In a molecular compound, atoms join together by sharing electrons in the highest energy level.

Consider the Bohr Diagrams for both Hydrogen and Oxygen (to make water):

Diatomic Molecules composed only of two atoms of the same element are Diatomic Molecules. Common diatomic molecules are Hydrogen, Nitrogen, Oxygen, and the halogens (Fluorine, Chlorine, Bromine, Iodine, and Astatine)

Physical State of Compounds Commonly a chemicals state at room temperature will be indicated behind the element compound as a subscript. S – solid, l – liquid, g – gas, aq – aqueous (dissolved in water)

Symbols The symbol of each element that is contained in a compound will be written in the chemical name of that compound Ex/ Na. Cl ***Remember – there are 1 or 2 letters in each compound symbol and the first letter is capitalized, the second is lowercase Therefore the two symbols in Na. Cl are Na and Cl, which means that Sodium and Chlorine are contained in Na. Cl

There are sometimes numbers behind a chemical symbol, these numbers show many atoms of each chemical are in the compound Ex/ H 2 O 2 Hydrogen and 1 Oxygen molecule WATER symbol for hydrogen H 2 O symbol for oxygen each molecule contains two atoms of hydrogen and one atom of oxygen

CARBON DIOXIDE symbol for carbon CO 2 no number, represents one atom of carbon symbol for oxygen each molecule contains two atoms of oxygen in each molecule CARBON MONOXIDE symbol for carbon CO one atom of carbon symbol for oxygen one atom of oxygen

Compound Element in compound Molecular or Ionic Number of Atoms in Each Drawing of Compound Element Ca. O Ca. Cl 2 Al 2 O 3 Na 2 O Al. Cl 3 Na. OH Calcium; Oxygen Calcium; Chlorine Aluminum Oxygen Sodium Oxygen Aluminum Chlorine Sodium Oxygen Hydrogen Ionic Ionic & Covalent 1 Calcium; 1 Oxygen 1 Calcium; 2 Chlorine 2 Aluminum 3 Oxygen 2 Sodium 1 Oxygen 1 Aluminum 3 Chlorine 1 Sodium 1 Oxygen 1 Hydrogen Cl O Ca Cl Ca Al O O Na Cl Al Al Cl Na O H Cl O

Chemical Formula Matter cannot be created or destroyed. In chemical equations, both sides must contain the same number of atoms of each element. Large numbers in front of a compound indicate how many molecules of the compound are used in the chemical equation.

Ex/ 2 CH 3 OH + 3 O 2 - 2 CO 2 + 4 H 2 O In CH 3 OH, there is 1 carbon, 4 Hydrogen, and 1 Oxygen and in O 2 there are 2 oxygen. The formula uses 2 of CH 3 OH molecules and 3 O 2, therefore on the left side of the formula… 2 – Carbon 8 – Hydrogen 8 – Oxygen On the left side of the equation, there are 2 molecules of CO 2 and 4 molecules of H 2 O. Therefore there are: 2 – Carbon 8 – Hydrogen 8 – Oxygen

Ex/ Mg + S Mg. S 24. 3 g 32. 1 g 56. 4 g