EU 2024 Year 8 Chemistry - Classifying and Representing Matter.pdf

Year 8 Chemistry Classifying and Representing Matter Learning INtentions We are learning to classify and represent different types of matter Success criteria Understand that atoms are the building blocks of all matter Explain the difference between an atom and an element Recognise that...

Year 8 Chemistry Classifying and Representing Matter Learning INtentions We are learning to classify and represent different types of matter Success criteria Understand that atoms are the building blocks of all matter Explain the difference between an atom and an element Recognise that all the elements have a chemical symbol PART 1: Structure of the Atom Atomic Theory Atomic theory The scientific theory that all matter is made of particles called ATOMS Atoms can combine to make new substances Bonds between atoms break and reform in chemical reactions (chemical changes) Glossary terms SUBATOMIC - means it is smaller than an atom Subatomic particles - the parts that make up an atom Structure of an atom An atom is made Electron cloud/ shell up of 3 SUBATOMIC parts: Neutrons Protons Electrons  Proton Neutron Electron py the table into your books Charge Positive (+) Neutral ( ) Negative (-) Location In the nucleus In the nucleus Orbiting around in the electron shells/cloud Mass 1 amu (atomic 1 amu (atomic Almost no mass mass unit) mass unit) Size of an atom Mass of the atom The nucleus is the “heavy” part of the atom ○ The protons and the neutrons are what gives the atom its mass because they are located in the nucleus Electrons have almost no mass so we don’t count them in the mass of the atoms Atomic mass = number of protons + number of neutrons in the atom If an atom has 5 protons and 5 neutrons what is its atomic mass? Consolidate Complete Stile lesson: Structure of an Atom PART 2: The Periodic Table The Periodic Table The classification and organisational system for elements. The rows are called periods The columns are called groups The elements are arranged in order of their atomic number Elements are also classified into groups according to their properties - the coloured groups. Representing Elements in the Periodic Table Elements have both a name and a chemical symbol. Element name: Hydrogen Chemical symbol: H Rules for chemical symbols. mass First letter is ALWAYS capitalised, if there is a second letter is ALWAYS lowercase. Eg. Cl = Chlorine, O = Oxygen Chemical Symbols Which of the following are accurate chemical symbols representing elements? Rules for chemical symbols. 1. Cl First letter is ALWAYS 2. B capitalised, if there is a 3. AU second letter is ALWAYS 4. He lowercase. Chemical Symbols Which of the following ARE NOT chemical symbols representing elements? Rules for chemical symbols. 1. O First letter is ALWAYS 2. bL capitalised, if there is a 3. AU second letter is ALWAYS 4. He lowercase. Navigating the periodic table - choose 5 other elements from the top 20 elements and complete the table Element Atomic Chemical Group # Period # (row) Group Name Number Symbol (column) Hydrogen 1 H 1 1 Non metal Atoms and the Periodic Table The periodic table is arranged in ascending (going up) atomic number The atomic number of an element = the number of protons the atom has Build an atom Complete the worksheet Atoms notes Protons = the ATOMIC NUMBER of an atom AND the TYPE of Atom Electrons = change overall net charge of an atom If there are less electrons than protons = positive charge If there are more electrons than protons = negative charge Neutrons = change the MASS of an atom Complete the table below Element Name Number of protons Checkpoint Complete the hardcopy quiz PART 3: Elements, Compounds & Mixtures Types of matter Elements Made up on ONLY ONE TYPE of atom Cannot be broken down Compound Made up of 2 or more DIFFERENT types of atoms chemically BONDED together Can be broken apart in a chemical reaction Mixtures 2 or more substances physically combined Which particle diagram represents what? Elements Made up on ONLY ONE TYPE of atom Compound Made up of 2 or more DIFFERENT types of atoms chemically BONDED together Mixtures 2 or more substances physically combined Element, compound or mixture A = ELEMENT B = COMPOUND C = COMPOUND D = _MIXTURE Classification of Elements Monoatomic elements Diatomic elements (mono means 1) (Di means 2) One atom Two of the SAME atom chemically joined Example: Hydrogen Example: Oxygen → O2 *there are only 3 polyatomic elements: selenium, sulphur and phosphorous. Practice Complete the following worksheet Making worms! Why we see “worms” Sodium alginate is a long chain of molecules called a polymer, made from many sugar molecules linked together. It comes from seaweed. Polymers are very large molecules made from smaller ones joined in a chain. When sodium alginate (the "Worm Goo") touches the Calcium solution (the "Worm Activator"), the liquid turns into a solid. Calcium ions (Ca²⁺) link the alginate chains together. This is called cross-linking. Calcium replaces sodium ions (Na⁺) and links the alginate chains, forming a solid strand that can't dissolve in the calcium solution. The reaction is so fast that the inside of the "worm" stays liquid while the outside forms a solid shell. It is a chemical change because New bonds are formed: The calcium ions (Ca²⁺) from the calcium chloride solution create new chemical links (cross-links) between the alginate polymer chains. This changes the structure of the alginate, turning it into a gel. Irreversible process: New substance: The result is a new substance (cross-linked alginate gel) with different properties, like being solid and insoluble, compared to the original sodium alginate solution. PART 3: Chemical Formula’s & Equations Chemical Formula In a chemical formula, We use the element symbols to identify which elements are present. Subscripts (little numbers at the bottom) to state how many atoms of each element exist within the compound. The subscript ONLY APPLIES to the element it is attached too. Example 1. In the chemical formula H2O a. What elements are present? b. How many of each element are there? Practice - identify… 1. CO2 ○ Elements in the compound: ______________________________ ○ Number of atoms for each element: _______________________________________ 2. CuCO4 ○ Elements in the compound: ______________________________ ○ Number of atoms for each element: _______________________________________ 3. CuCO3 ○ Elements in the compound: ______________________________ ○ Number of atoms for each element: ______________________________________ ANSWERS 1. CO2 ○ Elements in the compound: Carbon, Oxygen ○ Number of atoms for each element: 1 x carbon, 2 x oxygen 2. CuCO4 Elements in the compound: Copper, Carbon, Oxygen Number of atoms for each element: 1 x copper, 1 x carbon, 4 x oxygen 3. CuCO3 ○ Elements in the compound: Copper, Carbon, Oxygen ○ Number of atoms for each element: 1 x Copper, 1 x Carbon, 3x Oxygen Making compounds You will be using lollies to make models of compounds. You will need your periodic table AND you will need to research to find out the specific name of the compound and everyday uses. Chemical Equations Rules: The arrow must be pointing from the reactants to the products to show the direction of the reaction The arrow must NEVER be an equals (=) sign Identify which particle diagram represents the 2 substances that are combined in this reaction - explain your answer H + O2 → H2O Step 1 Identify which side of the arrow is the reactants. Step 2 Identify how many elements are involved - these are represented by the colours Step 3 Count the number of atoms for each element and match A B C D to the particle diagram ANSWERS H2 + O→ H2O It must be A and C because in the reactions there are is a single hydrogen atom and then two oxygen atoms bonded together. In A there are 2 of the same atoms bonded so this must be oxygen In C there are single atoms so this must be hydrogen A B C D Identify which particle diagram represents the PRODUCT in this reaction - explain your answer H2 + O→ H2O Step 1 Identify which side of the arrow is the products Step 2 Identify how many elements are involved - these are represented by the colours Step 3 Count the number of atoms for each element in the product compound and A B C match this to the compounds in the particle diagram ANSWERS H2 + O→ H2O It must be substance B because in the products of the reaction there are 2 hydrogen atoms bonded to one oxygen atom. There needs to be 3 atoms in each compound. This means it can only be B. A B C Identify which particle diagram represents the 2 substances that are combined in this reaction - explain your answer Cu + CO3 → CuCO3 Step 1 Identify which side of the arrow is the reactants. Step 2 Identify how many elements are involved - these are represented by the colours Step 3 Count the number of atoms for each element and match A B C D to the particle diagram Identify which particle diagram represents the 2 substances that are combined in this reaction - explain your answer Cu + CO3 → CuCO3 It must be b and c because there is one substance is an element, so only one type of particle and the other needs to have 3 of one type of atom A B C D Identify which particle diagram represents The PRODUCT in this reaction - explain your answer Cu + CO3 → CuCO3 Step 1 Identify which side of the arrow is the products Step 2 Identify how many elements are involved - these are represented by the colours Step 3 Count the number of atoms for each element in the product compound and A B C match this to the compounds in the particle diagram