General Chemistry Grade 11 PDF

GENERAL CHEMISTRY Chemical Properties - observed as the GRADE 11 change of identity of a substance into another substance through a chemical What is Chemistry?...

GENERAL CHEMISTRY Chemical Properties - observed as the GRADE 11 change of identity of a substance into another substance through a chemical What is Chemistry? change. It is the study of matter and the changes that matter undergoes. Intensive Properties - do not depend on 5 Main Branches of Chemistry the amount of matter being measured. Extensive Properties - depend on the amount of matter present. Values of the same extensive quantities can be added. The physical and chemical properties of matter are closely related to the two types of change that matter undergoes A physical change occurs when a substance alters its physical form, not its composition. For example, when ice melts, several properties are changed such as hardness and density but it's still water. Chemical changes, a chemical change, also called chemical reaction, occurs when the composition of a substance is changed and a new substance is formed. An example will be the browning of an apple when exposed to air. Properties of matter are broadly categorized based on the microscopic point of view Chemists distinguish among several (physical vs. chemical) and their subcategories of matter based on dependence on the amount of matter composition. The following are the present (extensive vs. intensive) classification of matter based on composition. Physical Properties - measured and observed without changing the composition of the substance Substance - A substance is a form of Any mixture whether homogeneous or matter that has a definite (constant) heterogeneous, can be created and then composition and distinct properties. separated by physical means into pure components without changing the identities Examples are water, ammonia, table sugar of the components. (sucrose), gold and oxygen Matter occurs commonly in three physical Types of more Substance forms called states: solid, liquid, and gas. 1)​ In element is substance that cannot be separated into simpler Solids - have a definite volume and substances by chemical means. maintain a definite shape. There is a strong force of attraction between the particles and An example would be gold, silver, and little free space between them making these oxygen. particles closely packed together rigid. 2)​ A compound is a substance Liquids - also have a definite volume, but composed of atoms of two or more do not have a definite shape instead they elements chemically united in fixed take the shape of their containers. The proportions. particles in a liquid are not as closely held together in solids and thus can slide past An example would be water which is each other. composed of 2 atoms of hydrogen and 1 atom of oxygen. Gases - have no definite volume and shape. Like liquids they take the shape of Compounds can be separated only by their container. The force acting on the chemical means into their pure components. particles of a gas is weak, which is why they tend to move past each other freely. They A mixture is a combination of two or more have a lot of free space between them, substances in which the substances retain making the gases flow. their distinct identities. Some familiar examples are air, soft drinks, milk, and cement Heterogeneous Suspension (components settles at the Types of Mixtures bottom) 1)​ A mixture is homogeneous when it Colloid (you can identify the components) has a uniform composition throughout. An example would be sugar dissolved in water. 2)​ A mixture is heterogeneous when it does not have uniform composition COMPONENTS OF A MIXTURE throughout. An example would be The components of a mixture are not sand mixed with iron filings. chemically bond thus, the components can be separated by physical means using MAGNETISM different separation techniques. Below are Is a method that uses magnets to remove examples of methods for separating magnetic solids from non-magnetic mixtures: components of a mixture. CHROMATOGRAPHY - is a method that FRACTIONAL DISTILLATION separates the components of a mixture by passing it through a medium in which the components move at different rates. It has a mobile phase that passes through a stationary phase that supports or holds the mixture to be separated. DECANTATION - is a method that can be used in two ways: to separate solids and liquids components and to separate two or more liquids. The decant (liquid free from solids) is poured off to have the precipitate (solid) behind ATOM DISTILLATION - is a method used in a pure An atom is the fundamental unit of matter. It liquid from a mixture of liquids through the consists of three primary subatomic process of evaporation and condensation. It particles : protons, neutrons, an electrons takes differences in the boiling point of substances to separate a homogeneous NUCLEUS mixture into its components. ​ The nucleus is the dense central core of an atom. It house both EVAPORATION - is a method used to protons and neutrons separate mixtures with one or more ​ PROTONS carry a positive charge dissolved solids. It involves heating and and contribute to an atom’s mass allowing the liquid components to and identity evaporate. ​ NEUTRONS are neutral particles that add to an atom’s mass but do not FILTRATION affect its charge. Is a method that separates suspended solids from a liquid mixture by passing ELECTRONS through the pores of a filter paper that lines ​ Electrons orbit the nucleus in shells a funnel. The liquid that passes through the or orbitals filter is called the filtrate. The solid that ​ They are negatively charged remains on the filter is called the residue. particles with negligible mass  ​ The number of electrons in an atom determines its chemical properties 2)​ ATOMIC NUMBER : this number, located as a subscript to the left of the symbol, represents the number of protons in the atom’s nucleus. It uniquely identifies the element. 3)​ MASS NUMBER: this number located as a superscript to the left of the symbol, represents the total number of protons and neutrons in In a neutral atom, the number of protons, the atom’s nucleus. equals the number of electrons EXAMPLE: Let’s take the example of Carbon -12. Its atomic symbol is : 12C6 HISTORICAL DISCOVERIES ​ PROTONS discovered by physicists C- this is the symbol for carbon Eugene Goldstein and Ernest 12- this is the mass number, indicating that Rutherford in 1910 Carbon-12 has 12 particles (protons and ​ ELECTRONS discovered by Joseph neutrons) in its nucleus John Thomson (J.J. Thomson) 6- this is the atomic number, indicating that ​ NEUTRONS discovered by James Carbon-12 has a protons in its nucleus Chadwick in 1932 ATOMIC SYMBOL An atomic symbol is a shorthand way of representing an element. It consists of one or two letters, usually derived from the element’s name. COMPONENT OF AN ATOMIC SYMBOL An atomic symbol typically includes three pieces of information: ISOTOPE Are different forms of the same element that 1)​ ELEMENT SYMBOL - this is the one have the same number of protons but or two-letter abbreviation for the different numbers of neutrons. element. This means they have the same atomic number (identifying the element) but different atomic masses. FOR EXAMPLE, “H” for Hydrogen, “C” for Carbon, and “Fe” for Iron Some isotopes are stable, meaning they do pipelines and industrial processes. This not decay over time. Others are unstable or helps industry leaks and optimize radioactive, and decay over time, emitting production. radiation. AGRICULTURE EXAMPLE CARBON ISOTOPES PLANT BREEDING. Scientist use radiation from isotopes to induce mutations in plants, Carbon is a common element found in many leading to the development of new crop substances, including our bodies and the air varieties with desirable traits like disease we breathe. It has three main isotopes: resistance and higher yields. Carbon 12: This is the common form of ARCHAEOLOGY AND GEOLOGY Carbon. It has 6 protons and 6 neutrons. RADIO CARBON DATING. Carbon-14, a Carbon 13: This isotope has 6 protons and radioactive isotope, is used to determine the 7 neutrons age of organic materials like wood, bone, and cloth. This helps archaeologists and Carbon 14: This isotope has 6 protons and geologists understand the history of Earth 8 neutrons. and human civilizations. While all three isotopes are carbon their ENVIRONMENTAL SCIENCE different numbers of neutron give them Water Tracing. Isotopes of hydrogen and slightly different properties. For example, oxygen in water molecules can be used to Carbon-14 is radioactive and is used in track the origin and movement of water carbon dating to determine the age of sources. This helps study climate change ancient objects. and water resource management. WHY ARE ISOTOPES IMPORTANT? Matters are composed of molecules or ions Isotopes have a wide range of applications held together by chemical bonds. across various fields. Here are some examples: A molecule is an electrically neutral group of two or more atoms held together by MEDICINE chemical bonds. It is the smallest particle in PET SCANS - radioactive isotopes like an element or compound that has the fluorine-18 are based on PET SCANS to chemical properties of the element or create images of organs and tissues. This compound. helps doctors diagnose diseases like cancer. EXAMPLES OF MOLECULES INCLUDE: INDUSTRY Water molecule which consists of 2 Radioactive. Isotopes like cobalt-60 are Hydrogen atoms and 1 Oxygen atom. used to track the flow of materials in Carbon Dioxide molecule which consists of 1 atom of Carbon and 2 atoms of 2. Space-filling models are more Oxygen. accurate in representing the size of the atoms but are more time-consuming to POLYATOMIC MOLECULE construct and do not accurately depict the Are molecules that contain three or more 3D positions of atoms. atoms. It could be made up of the same elements (e.g Ozone O3) or different Chemical formulas are used to elements (e.g. Water H20) express the composition of molecules and ionic compounds in terms of chemical DIATOMIC MOLECULE symbols. It indicates the number and kinds Are molecules that exist with only two of elements in the substance and can be atoms. It would be made up of the same represented as: elements (e.g. Oxygen O2) or different elements (e.g Carbon Monoxide CO) 1. Structural formula shows the atoms in the molecule and the bonds that hold these An Ion is an electrically charged atom or atoms together. group of atoms formed when an atom gains or loses an electron. The loss of one or 2. Molecular formulas show the actual more electrons from a neutral atom forms number of each element in a substance. an ion with positive charge and is referred to as cation. 3. Empirical formulas show the smallest whole number ratio that exists in a If a NEUTRAL ATOMS gains an electron it substance. The ratios are usually forms an ion with a negative charge and it is represented as subscripts. referred to as anion. MONOATOMIC IONS are ions made up of Water (H20) Methane (CH4) only one atom while those that one made up of two or more atoms are referred to as Ball-and-stick model Ball-and-stick model polyatomic ions. Molecular models are used to visually represent molecules and compounds in 3D space. There are two standard models used for representing molecules: Space-filling models Space-filling models 1. The ball-and-stick model is easy to construct and clearly shows the 3D arrangement of the atoms in a molecule but does not represent the accurate sizes of the atoms.  2. For cations with multiple charges such as Chemical formula is a way of copper, iron, and others (transition metals). representing substances in different Two naming methods can be used namely: chemical reactions. The number of atoms of an element in a chemical formula is a. Stock method which uses Roman indicated as its subscript Every chemical numeral number enclosed in a parenthesis has its name. Chemical nomenclature is the that indicates the charge of the cation system of labelling and naming a variety of EXAMPLES: chemical substances. Different types of FeCl2- Iron (II) Chloride (Fe+2) compounds follow different rules in naming. FeCl3- Iron (III) Chloride (Fe+3) Ionic Compounds b. Classical method which uses the ionic compounds are compounds that are classical name or old names of the cation made up of ions. ions are electrically and whose ending is replaced by -ous if it charged atoms and can be classified as has lower charge and -Ic for higher charge. positively charged known as cation and EXAMPLES: negatively charged known as anion. FeCl2- Ferrous chloride FeCl3- Ferric chloride Cations are usually metallic except for ammonium ions while anions are CATIONS AND ANIONS are components non-metallic. ions can be monatomic, that form ionic compounds. There are two meaning made up of a single element and types of ionic compounds: binary (made of polyatomic which is composed of two or two elements) ternary (made of three more elements. elements). These two are named in the same way. To have a given ionic compound, Naming ionic Compounds the cation name is stated first followed by the anion name. 1. Write the name of the first element a cation and followed by the name of the To write a chemical formula, the guidelines second element usually an anion with a should be followed: space in between. If the anion is 1)​ Write down ions which will combine to monoatomic, replace the ending of the element with -ide. But if an anion is form a compound. polyatomic, refer to the table "ions and their 2)​ Crisscross the charges of ions. The charges” in the periodic table and look for charges will be the subscripts of the names of the symbols. elements in the formula. If there is only one atom of an element, the number (1) is no longer written. EXAMPLES: 3)​ When there are polyatomic ions, use CaS - CALCIUM SULFIDE parentheses to separate them from NH4Cl - Ammonium chloride the subscript that indicates the Na3PO4 - Sodium phosphate number of ions in the formula. 4)​ The numerical subscript of the formula must be written its simplest  form by dividing the subscripts by 3)​ The second element’s name has an any common multiple. -ide ending. 4)​ The number of atoms in each EXAMPLE element is indicated by Greek prefixes. Prefix Meaning Mono 1 Di 2 Tri 3 Tetra 4 Penta 5 Hexa 6 Hepta 7 Octa 8 Nona 9 Deca 10 Binary Molecular Compounds Note: consists of two non-metal elements forming Prefix mono- should never be used in the covalent bonds. These are the following first element. When the prefix ends with an guidelines in naming binary molecular a or o and the name of the second element compounds: starts with a vowel, the prefix with an a or o is omitted. 1)​ The element’s name closest to the metals is usually written first. Examples: However, when a compound ​ Cl2O dichlorine Monoxide contains O and Cl, Br, or I (any halogen except F), halogens are ​ PN3 Phosphorus Trinitride written first and O last. ​ NCl3 Nitrogen Trifluoride 2)​ If both elements are situated in the ​ P4O10 Tetraphosphorus decoxide same column of the periodic table (referred to as ‘group’) the lower one ACIDS is named first. Are compounds that gives off hydrogen BASES ions when dissolved in water (aqueous) Are substances that yields by hydroxide and are easily recognized since - ions (OH ) when dissolved in water and are formulas usually begins with H. the easily recognized since formulas usually name of the acid depends on its end with OH. To have a base simply give physical state. the name of the first element and add the word hydroxide after. To name a binary acid in its aqueous form, the anion name is prefixed with EXAMPLES: hydro-, suffixed with -ic, and added the NaOH - Sodium hydroxide term acid. In gaseous form follow the KOH - potassium hydroxide rules for naming molecular compounds Hydrates HCl (GAS) Hydrogen Chloride Are compounds that have a specific number of water molecules attached to them. To HCl (AQUEOUS) Hydrochloric name hydrates, simply name compound Acid first, followed by hydrate (water molecule). Denote the number of molecules using H2S (GAS) Hydrogen Sulfate prefixes used in naming molecular compounds H2S (AQUEOUS) Hydrosulfuric Acid EXAMPLES: 2 LiCl (H O) Lithium Chloride Monohydrate Ternary Acids are formed when Srl (NO3)2 x 4H2O Potassium hydroxide hydrogen and polyatomic ions combine. The acid name is based on the In chemistry a mole (symbol, mol) of a polyatomic ion; the suffix -ite is replaced 23 with -ous, and the -ateis replaced with substance contains 6.02x10 -ic. representative particles. Ita is the SI unit for 23 the amount of substance and 6.02x10 is EXAMPLES: called Avogadro’s number named after Amadeo Avogadro who helped clarify the NO2 Nitrite difference between atoms and molecules. NO3 Nitrate HNO2 Nitrous Acid REPRESENTATIVE PARTICLES HNO3 Nitric Acid Refers to the species present in a SO3 Sulfite substance such as atoms, molecules, ions, or formula units. The representative SO4 Sulfate particles of most elements are the atom HSO3 Sulfurous Acid except for more elements that exist as a HSO4‘ Sulfuric Acid diatomic. This includes Hydrogen (H2), Nitrogen (N2), Extensive Properties: A physical property that will change if the amount of matter Oxygen (O2), Fluorine (F2), Chlorine (Cl2), changes. Bromine (Br2), and Iodine (I2) which is a molecule. Determining the amount of substance for moles and numbers of particles 1)​ To calculate how many representative particles are present in a mole of a substance use the following conversion factor. No. of representative particles = given 23 number of moles x = 6.02x10 representative particles / 1 mole https://mmerevise.co.uk/a-level-chemistry-re vision/fundamental-particles-electronic-confi guration/ (isotopes and radioactive) Physical properties can be observed or measured without changing the composition of matter. Physical properties are used to observe and describe matter. Physical properties of materials and systems are often described as intensive and extensive properties. This classification relates to the dependency of the properties upon the size or extent of the system or object in question. Intensive properties: A physical property that will be the same regardless of the amount of matter.