Particle Model & Atoms PDF

# Eva Norville ## **a** ### PARTICLE MODEL - The particle model is a theory of how scientists think that matter is made up. - It can be used to explain why matter behaves the way it does. ### Diagram - It has six diagrams and a statement associated with each diagram. - The first diagram shows a box...

# Eva Norville ## **a** ### PARTICLE MODEL - The particle model is a theory of how scientists think that matter is made up. - It can be used to explain why matter behaves the way it does. ### Diagram - It has six diagrams and a statement associated with each diagram. - The first diagram shows a box with the word "Cold" at the bottom left of the box and the word "Hot" at the bottom right of the box. - Inside the box are 10 circles, smaller than the box. - There are more circles clumped together on the right side of the box and less on the left side. - The second model has 10 circles with arrows pointed in different directions. - The third diagram has 10 circles with arrows pointing in different directions. - The fourth diagram has 10 circles with arrows pointing in different directions. - The fifth diagram has 10 circles with arrows pointing in different directions. - The sixth diagram has 10 circles with arrows pointing in different directions. ### Statement - **Matter is made up of tiny particles.** - **The particles in matter are in motion.** - **Increasing the temperature increases the amount of motion.** - **The particles in matter are attracted to each other. The attractions get stronger when particles are closer together.** - **The particles in matter are separated by empty space.** - **All particles in one type of matter are the same. Different types of matter are made of different particles.** ## **b** ### STRUCTURE Of THE ATOM - Atoms consist of three particles: - Electrons - Orbit the center of the atom (nucleus). - Are negatively charged. - Protons - Found in the nucleus. - Are positively charged. - Neutrons - Found in the nucleus. - Are neutral charged. - The elements on the periodic table all have their own number. - They are ordered by this number from lowest to highest. - **ATOMIC NUMBER**: The number of protons in an atom's nucleus. - For example, gold has an atomic number of 79, so it has 79 protons (positively charged particles) in the nucleus. - **ATOMIC MASS**: The number of protons AND neutrons in an atom's nucleus. - For example, Fluorine has atomic number 9 and a mass of 19. ## **c** ### The ATOM - Continued - **ATOMIC NUMBER**: The number of protons in the atom's nucleus. - **ATOMIC MASS**: The number of protons PLUS the number of neutrons in the atom's nucleus. - The number of ELECTRONS equals the number of PROTONS. - For example, SODIUM (Na) has 11 protons and 23 atomic mass. - 11 is the atomic number. - 23 is the atomic mass. - 11 is the number of electrons. - 12 is the number of neutrons. ## **d** ### Chapter 7 #### PUTTING ATOMS TOGETHER - Most things are not made of individual atoms. - They chemically join with other atoms to form small units called molecules. - **Chemical Formula**: Notation that indicates the type and number of atoms in a pure substance. - For example, the nitrogen molecule is N₂. - This means that two nitrogen atoms are attached to each other. - H₂O has two hydrogens and one oxygen atom attached to each other. - **Molecular Element**: A molecule consisting of atoms of the same element. - Examples: N₂,O₂,H₂,Cl₂ - There are seven diatomic elements in total - **Molecular Compounds**: Molecules that consist of two or more different elements. - For example, carbon dioxide (CO₂) is a molecular compound. - Sugar can be written as C₁₂H₂₂O₁₁. - It has 12 carbons, 22 hydrogens and 11 oxygens attached to each other. - **Ionic Compounds**: - Some are not molecules. That is, they are not composed of neutral atoms. - Some compounds are made up of charged particles called ions ## **j** ### PERIODIC TABLE PATTERNS - The periodic table is arranged in a particular way. - All the elements in the same column have similar physical and chemical properties. - **Chemical Family**: Elements in the same column of the periodic table belong to the same group, or chemical family. - There are 18 vertical columns in the periodic table (7 labeled groups 1-18) - **Alkali Metals**: - Group 1 on the left of the periodic table. - Shiny, silvery, soft, and highly reactive. - Present in many everyday substances such as sodium, potassium especially. - **Alkaline Earth Metals**: - Second column from the left. - Shiny and silvery but not as soft or reactive as the alkali metals. - Magnesium and calcium are part of this group. - **Noble Gases**: - Most stable elements in the periodic table. - They are colorless, odorless, and tasteless. - They are found as single atoms and do not react with other elements. - Found in group 18. - **Halogens**: - Second column from the right. - Very reactive. - Can be poisonous in large amounts in their elemental form. - Examples are fluorine, chlorine, bromine, and iodine. - **Hydrogen**: - Group of one. - Very reactive gas. - The only gas located with the metals at the top left corner. - **Metalloids**: - Also called semi-metals - Found along the “staircase” (border between metal and non-metals). - Have intermediate properties of both metals and non-metals. ## **k** ### PERIODIC TRENDS - Elements in the same column share some chemical and physical properties. - Elements in the same horizontal row (periods) show some trends of increasing or decreasing reactivity. - You can use these facts to predict which element is more reactive than the other. ## **l** ### PERIODIC TABLE PATTERNS - If you draw Bohr Rutherford diagrams for all the atoms in the first column on the left (called the alkali metals), they will all have ONE electron in the outer shell. - This is why they behave chemically similar to each other and are in the same group. - If you draw diagrams of the second row from the left, they all contain TWO on the outer orbit. - If you draw diagrams of the far right column, they all contain FILLED outer shells. - This is why the noble gases don't react with other atoms — they are stable. ## **m** ### PRODUCING LIGHT - Scientists noticed that when you take atoms and expose them to thermal (heat) energy or electricity, they produce light of different colours. - **Shells**: The "shells" are paths that electrons normally orbit around the nucleus in, - Electrons that orbit the closest have the lowest energy. - Electrons that orbit farther away have higher energy. - They are like planets in the solar system orbiting the Sun. - **Excited State**: When energy is given to the atom, it causes electrons to "jump" up to a higher energy level as they absorb the new energy given to them. - **Ground State**: When they go back to their original spot (called the ground state), they release the energy they absorbed in the form of light, or colour. - **Electrons and Atoms**: Each atom has different arrangements of electrons, so each element produces different colours. ## **e** ### IONS - An ion forms when an atom loses or gains more electrons without changing its number of protons. - **Cation**: Positively charged ion. - An atom loses electrons (negative charges) but keeps the amount of protons constant (positive charges) in the nucleus. - **Anion**: Negatively charged ion. - When atoms gain negatively charged electrons, the excess negative charge makes the atom a negatively charged ion. - **Sodium**: Typically loses one electron, resulting in a +1 charge. - It contains 11 positive charges and 10 negative charges. - **Chlorine**: Typically gains an electron, resulting in a -1 charge. - The chloride ion has one extra negative charge. - **Transferring Electrons**: Sodium transfers its electron to chlorine in an ionic bond. ## **f** ### IONIC BONDS - The reason why sodium transfers one electron is that atoms always want to look like they have a full outer orbit of electrons. - **Sodium**: Only has one on its outer orbit, so it loses it. - **Chlorine**: Normally has 7 electrons in its outer orbit. It is more stable when the outer orbit is full. - It tends to gain one electron to make the outer orbit have 8. - **The Sodium**: Becomes positively charged. - **The Chlorine**: Becomes negatively charged. - **Ionic Bond**: They hold themselves together. - **Sodium Chloride**: Sodium and chlorine work together to perfectly form it. - The chemical formula is NaCl. - **Ionic Compounds**: A compound that consists of positively and negatively charged ions. ## **g** ### CHEMISTRY CHAPTER 6 #### Questions - **Periodic Table - Metals/Non-Metals** - Explain the significance of the bold "staircase" line on the periodic table. - Are there more metallic elements or non-metallic elements listed on the periodic table? - List three properties of metals. - List three properties of non-metals. - Create a two-column table with the headings "Metals" and "Non-metals". Classify each of the following properties as characteristic of metals or non-metals. - Conducts Electricity - Gas under normal conditions - Can be flattened by hammering - Is located in the upper-right corner of the periodic table. - Shatters when struck - Dull yellow powder - Soft and shiny - Located in the first column of the periodic table - **Patterns in the Periodic Table** - Name the chemical family to which each of the following elements belongs: - Chlorine - Magnesium - Potassium - Helium - Sodium is a metal, like copper. Suggest two reasons why sodium cannot be used for electrical wires. - Alkali metals are found in many common substances but are rarely found in pure form. Explain why this is the case. - List an application for an element belonging to the halogen group - **Theories of the Atom** - Rutherford's experiment consisted of beaming positively charged particles at thin gold foil. - What did he expect to happen to the particles? - Why did the results surprise him? - From these results, what particles were proposed as part of an atom? - According to Rutherford, where in an atom are these particles located? - Is it reasonable to expect that these models will change again in time? Explain. - How is J.J. Thomson's atomic model different and also similar to Rutherford's model? ## **s** ### NAMING - MOLECULAR COMPOUNDS - Remember, a non-metal with a non-metal. - For example, the compound SO₃ would be called: - **Sulphur trioxide** - Notice that with the first atom you just write the name of the element. - The second atom you write the name, but ending in "-ide". - To say how many atoms there are for each element in the formula, use these prefixes for naming: - **Mono**: 1 - **Di**: 2 - **Tri**: 3 - **Tetra**: 4 - **Pent**: 5 - **Examples**: - **CO₂**: Carbon dioxide - **CO₃**: Carbon trioxide - **SO₄**: Sulphur tetroxide - **PCl₅**: Phosphorus pentachloride - **N₂O₄**: Dinitrogen tetroxide ## **t** ### WORKSHEET - NAMING MOLECULAR COMPOUNDS - Name these compounds, which all end in "-ide" and use the prefixes: - **NO₃**: Nitrogen trioxide - **SO₂**: Sulphur dioxide - **N₂O₄**: Dinitrogen tetroxide - **PCl₃**: Phosphorus trichloride - **SF₂**: Sulfur difluoride - **CO**: Carbon monoxide - **CO₂**: Carbon dioxide - **CO₃**: Carbon trioxide - **PO₄**: Phosphorus tetroxide - **SBr₅**: Sulfur pentabromide - **OCl₂**: Oxygen dichloride ## **u** ### NAMING - IONIC COMPOUNDS - Remember, a metal with a non-metal. - For example, the compound NaCl would be called: - **Sodium Chloride** - Notice that with the first atom you just write the name of the element. - The second atom you write the name, but ending in "-ide". - **Examples**: - **KBr**: Potassium bromide - **MgO**: Magnesium oxide - **NaF**: Sodium fluoride - **K₂O**: Potassium oxide - **AlCl₃**: Aluminium chloride ## **v** ### WORKSHEET - NAMING IONIC COMPOUNDS - Name these compounds, which all end in "-ide". - **NaCl**: Sodium chloride - **MgO**: Magnesium oxide - **MgCl₂**: Magnesium chloride - **Li₃N**: Lithium nitride - **KBr**: Potassium bromide - **K₂O**: Potassium oxide - **BeF₂**: Beryllium fluoride - **MgF₂**: Magnesium fluoride - **Li₂S**: Lithium sulfide - **Na₃P**: Sodium phosphide - **Be₃N₂**: Beryllium nitride ## **h** ### HOW ATOMS COMBINE - Atoms combine to become more stable. - The most stable elements in the periodic table are the noble gases because they all have the maximum number of electrons in their outermost orbits. - **Noble Gases**: Atoms that do not have the maximum number of electrons in their outermost orbits combine with other elements to obtain this maximum number of electrons. - **Metals and Metals**: - Mixtures of metals are called alloys. - They are basically solutions of metals that were melted together. - They do not combine chemically. - **Metals and Non-Metals**: - They are IONIC compounds. - Metals lose electrons and non-metals gain them, forming ions. - **Ionic Bond**: The cations attract the anions because they have opposite charges. The transfer of electrons from one atom to another results in an ionic bond. - **Naming**: To name ionic compounds, just add "-ide" to the end of the last element name. - **Example**: The compound MgO is Magnesium oxide, instead of "magnesium oxygen". - **Non-metals and Non-metals**: - These are molecular compounds. - Electrons are shared, not lost or gained from atom to atom. - They join close together so that their outer electrons all add up to a full outer orbit. - **Example**: Hydrogen can share its electrons to give both hydrogens a full outer orbit. ## **q** ### BOHR - RUTHERFORD DIAGRAMS - A Bohr- Rutherford diagram is a simple drawing that shows the numbers and locations of protons, neutrons, and electrons in an atom. - **Fluorine**: - Atomic number is 9. - 9 p⁺ - 10 n⁰ - The atomic mass is 19. - 19 - 9 = 10 neutrons. - When drawing electrons, they are placed in circular orbits around the nucleus. - 9 electrons. - There are 2 in the first orbit and 7 in the second. - **Phosphorous**: - Atomic number is 15. - Atomic mass is 31. - **Nucleus**: - 15 p⁺ - 16 n⁰ - **Electrons**: - 2 are in the first orbit. - 8 are in the second orbit. - 5 are in the third orbit. ## **w** ### LAB - BUILDING MODELS OF MOLECULES - There are three coloured spheres (atoms) that you will use for this lab: - **White**: Hydrogen - H - 1 connection - **Red**: Oxygen - O - 2 connections - **Black**: Carbon - C - 4 connections - **Types of Springs**: - **Short**: Represent a single bond. Most bonds are singles. - **Long/Double**: Represent a double bond. You need two long springs for a double bond. - **Drawing Molecules**: Straight lines are used to show the bonds. - **Example**: The molecule CH₄ is drawn like: H - H-C-H - H - **Part I**: Make the following molecules. When your group is finished, let your instructor know so he/she can come around and check. All the holes need to be filled up to know you are correct, if there are holes left over, double bonds are needed to fill them (long springs). - **CH₄**: Methane - **C₂H₆**: Ethane - **CO₂**: Carbon Dioxide - **C₂H₂**: Acetylene - **H₂O**: Water - **C₃H₈**: Propane - **O₂**: Oxygen - **H₂**: Hydrogen ## **r** ### WRITING FORMULAS - In the case you need to combine atoms where there is a metal (the first word in the chemical name is a metallic element), it is an ionic compound. - You will need to know what charges each atom can have on them. - **Example**: - Suppose you want to join SODIUM and CHLORINE together. - **Sodium**: Looking at the table, you notice Sodium is going to get a +1 charge. - **Chlorine**: Looking at the table, you notice Chlorine is going to get a -1 charge. - **Formula**: The IONS join together because +1 and -1 perfectly add to zero giving a neutral charge. The formula for this is NaCl. - **Example**: Suppose you want to join MAGNESIUM and FLUORINE together. - **Magnesium**: Looking at the table, you notice Magnesium is going to get a +2 charge. - **Fluorine**: Looking at the table, you notice Fluorine is going to get a -1 charge. - **Formula**: The formula is MgF₂ (or switch the charge numbers for the formula numbers) because one magnesium joins with TWO fluorine atoms. This is because a +2 charge can cancel out two -1 charges to make it overall zero charge. ## **i** ### STANDARD ATOMIC NOTATION - Element symbols for atoms can be written in a special way. - It can indicate lots of information about a particular atom. - **Example**: The symbol shown here shows the element Sodium (Na), in standard atomic notation. - **Atomic Number**: If you look sodium up on the periodic table, it is atomic number 11. - **Atomic Mass**: It also has an atomic mass of 23 - **Symbol**: Na - **Atomic Number**: 11 - **Mass Number**: 23 - **Charge**: + - **Ions**: The charge is indicated on the top right, and charged atoms are also called "ions". - **Neutral**: If there is no charge written, the atom is neutral. - **Example**: Atoms are neutral if they have the same number of protons and electrons. - **Gaining Electrons**: If atoms gain extra electrons, they get a negative charge, because the negative electrons outnumber the protons. - **Losing Electrons**: If atoms lose electrons, they get a positive charge, because the number of protons in the nucleus is now greater than the number of electrons. - **Summary**: - Gain electrons: atom gets a negative charge. - Lose electrons: atom gets a positive charge. - **Charge Notation**: If the charge is +1 or -1, normally the "1" isn't written so it looks like just a "+" or "-" instead. - **Charge Greater than 1**: Sometimes, if the charge is greater than 1, for example, +3, it can be written "+3" or "3+".