Grade 8 Chemistry Review Packet (Nov 26)

**Review Packet For Grade 8 Test** To help you prepare for the upcoming **Test,** Read through all the slideshows on class drive, your notes and read through this review packet thoroughly! **DO NOT WAIT till the last day -- it will be too much!** **Atomic Structure** 1. **What is the atomic numb...

**Review Packet For Grade 8 Test** To help you prepare for the upcoming **Test,** Read through all the slideshows on class drive, your notes and read through this review packet thoroughly! **DO NOT WAIT till the last day -- it will be too much!** **Atomic Structure** 1. **What is the atomic number of an element, and where is it found on the periodic table?\ Ans:** The atomic number is the number of protons/electrons in an atom\'s nucleus. Atomic Number & Mass Number - Atomic Number Definition, Facts, Videos & Calculations with Examples and FAQs 2. **If an atom has 11 protons, 12 neutrons, and 11 electrons, what is its atomic mass and atomic number?**\ **Ans:** Atomic number = 11 3. **What does the electron configuration tell us about an atom?\ Ans:** It shows the arrangement of electrons in the atom's energy levels or shells.  **Periodic Table** Features of the Groups and Periodic trends in properties --- lesson. Science State Board, Class 10. 6. **What are the elements in Group 1 known as, and why?\ Ans:** They are called alkali metals because they form alkaline solutions when they react with water. 7. **How do elements in the same group compare in terms of properties?**\ **Ans:** They have similar chemical properties and the same number of valence electrons. 8. **What do elements in Period 3 have in common?\ Ans:** They all have three electron shells. 9. **Which group contains the noble gases, and what is unique about them?\ Ans:** Group 18/8; they are stable and rarely react due to having full outer electron shells. ( stable octet) **Electron Configuration** 11. **What is the electron configuration of a neutral oxygen atom?\ Ans:** 2,6 12. **How many electrons can the second shell hold?\ Ans:** 8 electrons. 13. **What is the electron configuration for an atom with atomic number 12?\ Ans:** 2,8,2 14. **Write the electron configuration for chlorine (atomic number 17).**\ **Ans:** 2, 8, 7 15. **How many valence electrons ( electrons in the last shell) does sulfur have**?\ **Ans:** 6 valence electrons.  **Metallic Bonding and Alloys** 16. **Explain why metals are good conductors of electricity.\ Ans:** Metals have a \"sea of electrons\" that can move freely, ( delocalized sea of electrons) allowing them to conduct electricity. 17. **How does the \"sea of electrons\" model explain the malleability of metals?**\ **Ans:** The electrons can shift and move around, allowing metal atoms to slide past each other without breaking bonds. 18. **Why do metals typically have high melting and boiling points?\ Ans:** Strong metallic bonds require a lot of energy to break. **Naming and Formulas of Ionic Bonding** Compound Names & Formulas - ppt download  Ionic Formulas: Criss-Cross Method \| Science, Chemistry \| ShowMe 21. **Name the compound formed between potassium and chlorine.\ Ans:** Potassium chloride (KCl). 22. **Write the formula for calcium oxide. ( use ionic charges and cross method to create formulas)\ Ans:** CaO. 23. **What is the name of MgCl₂?\ Ans:** Magnesium chloride. 24. **If sodium and sulfur bond, what compound forms, and what is its formula?\ Ans:** Sodium sulfide (Na₂S). 25. **Write the formula for aluminum sulfate. ( use polyatomic chart)\ Ans:** Al₂(SO₄)₃. 26. **Write the name for CuSO4?** **Naming and Formulas of Covalent Bonding**  26. **Name the compound with the formula CO₂.\ Ans:** Carbon dioxide. 27. **What is the formula for dinitrogen tetraoxide?\ Ans:** N~2~O~4~. 28. **How would you name PCl₃?\ Ans:** Phosphorus trichloride. 29. **Write the formula for sulfur hexafluoride**.\ **Ans:** SF~₆.~ 30. **What is the name of the compound with the formula N₂O₅?\ Ans:** Dinitrogen pentoxide. **Drawing Diagrams of Ionic Bonding** 31. **Draw the ionic bond between calcium and oxygen.\ Ans:** Calcium transfers two electrons to oxygen, forming Ca²⁺ and O²⁻. 32. **Draw the electron transfer for the formation of NaCl.\ Ans:** Sodium donates one electron to chlorine, forming Na⁺ and Cl⁻. 33. **Explain the transfer of electrons in the ionic bond between K and F.**\ **Ans:** Potassium donates one electron to fluorine, resulting in K⁺ and F⁻. 34. **Show how an ionic bond forms between aluminum and chlorine.\ Ans:** Aluminum donates three electrons to three chlorine atoms, forming Al³⁺ and three Cl⁻ ions. 35. **Draw the ions formed in the bonding between magnesium and sulfur.\ Ans:** Magnesium donates two electrons to sulfur, resulting in Mg²⁺ and S²⁻. **Drawing Diagrams of Covalent Bonding** 36. **Draw the covalent bond in a water (H₂O) molecule.**\ **Ans:** Each hydrogen shares one electron with oxygen, f orming two single bonds. 37. **Show the sharing of electrons in an oxygen molecule (O₂).\ Ans:** Each oxygen atom shares two electrons with the other, forming a double bond. 38. **Draw a diagram of the covalent bond in CH₄.**\ **Ans:** Carbon shares one electron with each hydrogen, forming four single bonds. 39. **Draw the Lewis structure for a nitrogen molecule (N₂).\ Ans:** Each nitrogen atom shares three electrons, forming a triple bond. **Law of Conservation of Mass** 41. **Explain the law of conservation of mass with an example.**\ **Ans:** Mass is not lost or gained in a reaction. For example, burning wood forms ash, CO₂, and water vapor; the total mass remains constant. 42. **Why is the total mass of reactants equal to the total mass of products?\ Ans:** Because atoms are neither created nor destroyed, only rearranged. 43. **If 5 grams of hydrogen reacts with 20 grams of oxygen, what is the mass of water produced?**\ **Ans:** 25 grams. Due to law of conservation of mass, the amount of reactants = amount of products 44. **Balancing Equations** **Answers**  45. **Types of Chemical Reactions** Parts/Types of Chemical RXN - SSC Chemistry 46. **What products are formed when magnesium reacts with hydrochloric acid?\ Ans:** Magnesium chloride (MgCl₂) and hydrogen gas (H₂). 47. **Predict the products for zinc and sulfuric acid.\ Ans:** Zn + H~2~SO~4~ à ZnSO₄ ( Zinc Sulphate) and H₂ ( hydrogen) 48. **Will copper react with hydrochloric acid? Why or why not? How do you know?\ Ans:** No, copper is less reactive than hydrogen and won't displace it in hydrochloric acid. **Reactivity series** is a list of metals arranged in decreasing order of their reactivity. Most reactive metals are at the top while the least reactive metals at the bottom. 49. **What are the products of calcium reacting with nitric acid?\ Ans:** Calcium nitrate Ca(NO₃)₂ and hydrogen gas (H₂). 50. **Predict the products for iron reacting with sulfuric acid.\ Ans:** Iron sulfate (FeSO₄) and hydrogen gas (H₂). 51. **Predict the products for Hydrochoric acid reacting with sodium carbonate** 52. **What is a neutralisation reaction?** 53. Differentiate between exothermic and endothermic reactions. Difference between Endothermic and Exothermic Reactions \| Chemistry 54. Properties of ionic and covalent compounds  55. You will be also given a graph and a table to analyse and answer questions on it. 15 Motivational Quotes From Legends in Sports \| Entrepreneur