Chemistry Final units 1-4

STRATEGY

• Start by reading through your notes to refresh your memory on the topics.

• Use this review sheet to identify areas that require more study time.

• Refer back to homework assignments, classwork, and Quizizz for additional assistance.

• Ensure you understand why an answer is correct, not just what the answer is.

• Avoid copying a friend’s work as it won't aid in passing the Final Exams.

Day 1: Comprehensive Questions

1. Isotope Symbols: Imagine atoms are like LEGO bricks. An isotope symbol is like giving a special label to a specific LEGO brick. This label tells you how heavy the brick is (its 'mass number') and what kind of LEGO brick it is (its 'atomic number', like if it's a red brick or a blue brick).

   • a. Carbon-14: This Carbon brick is extra heavy! Its label is $^{14}_6C$

   • b. Chromium-53: This Chromium brick has a weight of 53! Its label is $^{53}_24Cr$

   • c. Nickel-63: This Nickel brick is somewhat heavy at 63! Its label is $^{63}_28Ni$

   • d. Zirconium-92: This Zirconium brick is quite heavy, weighing 92! Its label is $^{92}_40Zr$

2. Complete the Table for the following atoms, ions, and neutral atoms: Think of atoms as tiny houses with different rooms. We need to count the 'people' inside. Protons are like the parents in the main room, electrons are like the kids that can move around, and neutrons are like quiet grandparents. The 'atomic number' tells us how many parents, and 'mass number' tells us the total parents and grandparents.

   • Chemical Symbol: Zn (Zinc)

     • Atomic #: 30 (Meaning 30 protons, like 30 parents)

     • Mass #: 65 (Meaning 30 protons + 35 neutrons, like 30 parents + 35 grandparents)

     • # of Protons: 30

     • # of Electrons: 30 (Since it's a neutral atom, parents = kids)

     • # of Neutrons: 35 ($65 - 30 = 35$)

     • Atom, Ion, or Isotope?: Atom (It's a regular, neutral atom because parents and kids are equal).

3. Metals and Ions: Metals are like givers! They like to get rid of their 'kids' (electrons) to become happy and stable. When they lose kids, they become a bit more positive (like good givers!), and we call them 'cations'.

   • Metals tend to form cations by losing electrons, resulting in a positively charged ion.

   • This occurs because metals have a tendency to have fewer electrons in their outer shell, making it energetically favorable to lose them (it's easier to give away a few than to try and get many more).

4. Nonmetals and Ions: Nonmetals are like takers! They love to grab 'kids' (electrons) from others to complete their family and become happy and stable. When they gain kids, they become a bit more negative (like having extra kids!), and we call them 'anions'.

   • Nonmetals tend to form anions by gaining electrons, resulting in a negatively charged ion.

   • Nonmetals have a higher electronegativity, facilitating the gain of electrons to achieve a stable electron configuration.

5. Identifying Elements: To find out what kind of atom it is, you only need to count the 'parents' (protons)! That's its special identifying number.

   • The element with 50 neutrons, 36 electrons, and 38 protons is Krypton (Kr) (because it has 38 protons).

6. Group 5 Element: The 'group' tells us something about its family. Again, to know which element it is, we just count the 'parents' (protons).

   • The element in Group 5 with 16 neutrons, 18 electrons, and 15 protons is Phosphorus (P) (because it has 15 protons).

7. Neutral Atom vs. Ion: Imagine an atom is a team. If the number of positive players (protons) equals the number of negative players (electrons), the team is 'neutral' - no overall score. If the numbers are different, the team has a 'score' and is called an 'ion'.

   • A neutral atom has an equal number of protons and electrons, resulting in a charge of zero.

   • An ion is an atom with an unequal number of protons and electrons, resulting in a positive or negative charge.

8. Relationship Explanation: More important words for our atom family!

   • Isotope: Atoms of the same type of LEGO brick (same protons), but some are a bit heavier or lighter because they have a different number of quiet grandparents (neutrons).

   • Proton determines the atomic number: The number of 'parents' (protons) always tells you what kind of atom it is.

   • The mass number is the sum of protons and neutrons: The total weight of the atom (mass number) is found by adding the 'parents' (protons) and 'grandparents' (neutrons): $\text{Mass Number} = \text{Protons} + \text{Neutrons}$

9. Changing Charge of an Atom: We can only change the 'score' of our atom team by having kids (electrons) join or leave. We can't change the parents (protons)!

   • The charge of an atom can be changed by the gain or loss of electrons, resulting in anion or cation formation respectively.

10. Bohr Model: The Bohr model is like drawing a picture of an atom and showing its 'kids' (electrons) flying around in specific paths, like planets around the sun. Atoms try to have a full outer path of kids, just like a noble gas, to be super happy!

    • a. Lithium (Li): It has 3 electrons, but it's happier if it loses 1 to be like Helium (He), which has 2.

    • b. Magnesium (Mg): It has 12 electrons, but it's happier if it loses 2 to be like Neon (Ne), which has 10.

    • c. Nitrogen (N): It has 7 electrons, but it's happier if it gains 3 to be like Neon (Ne), which has 10.

    • d. Sulfur (S): It has 16 electrons, but it's happier if it gains 2 to be like Argon (Ar), which has 18.

11. Electron Excitation: Imagine a kid (electron) on a swing. If you give the swing a big push (absorb energy), the kid goes higher (higher energy level)! When the kid lets go and the swing comes down (releases energy), they might shout or glow a little (release light).

    • An electron becomes excited by absorbing energy, which elevates it to a higher energy level.

    • When the electron returns to the ground state, it releases energy, often in the form of light.

12. Electron Configuration: This is like writing down the address for all the 'kids' (electrons) in an atom. It tells you exactly which 'rooms' ($s, p, d, f$ orbitals) they are in and how many are in each room.

    • The given electron configuration $1s^22s^22p^63s^23p^64s^1$ adds up to 19 electrons. This is the electron address for the element Potassium (K).

13. s, p, d, and f Blocks location in the periodic table: The periodic table is like a big apartment building for atoms. Different sections are called 'blocks' based on where the last 'kid' (electron) moved in.

    • s-block: These are the first two rows (Groups 1 and 2) on the left side, where the 's' room is being filled.

    • p-block: These are the groups on the right side (Groups 13-18), where the 'p' room is being filled.

    • d-block: These are the transition metals (Groups 3-12) in the middle, where the 'd' rooms are being filled.

    • f-block: These are the two special rows at the very bottom (Lanthanides and Actinides), where the 'f' rooms are being filled.

14. Electron and Noble Gas Configuration: This is like giving the full address of all the kids, or a shortcut address! The shortcut (noble gas configuration) uses the name of a super-happy, stable atom (noble gas) that has most of the same kids, and then just lists the additional kids.

    • a. Sodium (Na): Full address: $1s^22s^22p^63s^1$; Shortcut address: $[Ne]3s^1$ (meaning it's like Neon, but with one extra electron in the $3s$ room).

    • b. Carbon (C): Full address: $1s^22s^22p^2$; Shortcut address: $[He]2s^22p^2$ (like Helium, with extra electrons in $2s$ and $2p$ rooms).

    • c. Molybdenum (Mo): Full address (simplified): $[Kr]5s^24d^5$; Shortcut address: $[Kr]5s^24d^5$

    • d. Selenium (Se): Full address: $[Ar]4s^23d^{10}4p^4$; Shortcut address: $[Ar]4s^23d^{10}4p^4$

15. Trends Definitions: Imagine a lineup of atoms. We can see patterns in how big they are, how sticky they are, or how hard it is to take their kids. These are 'trends' on the periodic table.

    • a. Atomic Radius: This is how big an atom is, like measuring its belly button to its outermost edge.

      • Trend: Atoms get bigger as you go down a group (more layers of 'kids'), but they get smaller as you go across a period (the 'parents' pull the kids in tighter).

      • Explanation: Atoms grow larger due to higher energy levels (more electron shells) and increased shielding effect (inner electrons block the pull from the nucleus a bit). When the parents pull harder without more shielding (across a period), they shrink.

    • b. Ionization Energy: This is how much energy you need to convince an atom to give up one of its outermost 'kids' (electrons).

      • Trend: It gets harder (more energy needed) as you go across a period (kids held tighter), but easier as you go down a group (kids are further away and easier to grab).

      • Explanation: As atomic radius decreases, electrons are more tightly held by the nucleus, making removal more difficult. When they are further away (down a group), it's easier to remove them.

    • c. Electronegativity: This is how 'sticky' an atom is (how much it wants to pull in other atoms' 'kids' when they are sharing).

      • Trend: Atoms get stickier as you go across a period, but less sticky as you go down a group.

      • Explanation: Increased positive charge in the nucleus attracts electrons more strongly as the atom gets smaller (decreases in radius).

16. Comparative Atomic Radius: Let's practice judging atom sizes!

    • a. Be or N: Be (Beryllium is bigger because it's further left in the row).

    • b. Ne or Xe: Xe (Xenon is bigger because it's further down in the column).

17. Comparative Atom/Ion Radius: What happens to size when an atom gains or loses a 'kid'?

    • a. Cl or Cl⁻: Cl⁻ (When Chlorine gains a kid, it gets bigger because the kids push each other away more).

    • b. Mg or Mg²⁺: Mg (When Magnesium loses kids, it gets smaller).

18. First Ionization Energy Comparison: Which atom holds its first outer 'kid' tighter?

    • a. Li or Cs: Li (Lithium holds its electron tighter because it's a smaller atom and the electron is closer).

    • b. Ca or As: As (Arsenic holds its electron tighter because it's further right in the periodic table, so it has more protons pulling).

19. Electronegativity Comparison: Which atom is stickier?

    • a. Cl or Si: Cl (Chlorine is stickier because it's further right and smaller).

    • b. O or Po: O (Oxygen is stickier because it's higher up and smaller).

20. Bond Types: When atoms hold hands, how do they do it? Do they grab the kids entirely, or just share them?

    • a. MgO: Ionic (Magnesium and Oxygen are very different, so Oxygen takes kids from Magnesium).

    • b. LiCl: Ionic (Lithium and Chlorine are very different, so Chlorine takes kids from Lithium).

    • c. H₂O: Polar covalent (Hydrogen and Oxygen share kids, but Oxygen pulls them a little closer to itself).

    • d. Br₂: Nonpolar covalent (Two Bromine atoms share kids perfectly evenly because they are the same).

21. Bonding Characteristics: Here's how we can tell what kind of hand-holding is happening:

    • a. Transfer of electrons: When kids are completely taken by one atom, it's Ionic (I).

    • b. Malleable with high melting points: These are metals, which usually have Metallic (M) bonds (like a big pool of shared kids).

    • c. Do not conduct electricity, low melting points: These are atoms that truly share kids in small groups (molecules), called Covalent (C) bonds.

    • d. Crystal lattice structure: This is a very organized, repeating pattern, typical of Ionic (I) compounds.

    • e. Sharing electrons: When kids are shared between atoms, it's Covalent (C).

22. Lewis Structure for MgO: A Lewis structure is like drawing a picture of how atoms hold hands by showing their outer 'kids' (valence electrons) as dots. For MgO, Magnesium (a giver) gives its two outer kids to Oxygen (a taker) to make them both happy.

    • $[Mg]^{2+} [:\text{O}:]^{2-}$ (Oxygen with 8 dots around it).

23. Lewis Structure for H₂O: For H₂O, Oxygen (a taker) shares its extra kids and also shares two kids with each Hydrogen (a giver) to make everyone happy.

    • H : Ö : H (Oxygen shares one electron with each Hydrogen, and has two extra pairs of electrons not being shared).
      ¨

24. Bond Formation: Why do atoms even bother to hold hands? They do it to become stable and happy, like a noble gas, where their outer path of 'kids' is full!

    • Atoms form bonds to achieve a full outer electron shell for stability, often resulting in lower energy configurations.

25. Bond Types Explanation: A deeper look at how atoms hold hands:

    • Nonpolar Covalent: This is when atoms share their 'kids' (electrons) perfectly evenly, like splitting a sandwich exactly in half. No one gets more than the other.

    • Polar Covalent: This is when atoms share their 'kids', but one atom is a bit stronger and pulls the shared kids a little closer to itself, like one friend getting a slightly bigger piece of the sandwich. This makes one side of the bond slightly negative and the other slightly positive.

    • Ionic Bonds: This is when one atom completely takes 'kids' from another atom! So one atom becomes fully positive, and the other becomes fully negative, and then they stick together because opposites attract.

26. Chemical Formulas for the following compounds: These are like secret codes that tell you exactly what atoms are in a compound and how many of each are there.

    • a. Calcium Bromide: $CaBr_2$

    • b. Iron(III) Sulfate: $Fe<em>2(SO</em>4)_3$

    • c. Lithium Phosphate: $Li<em>3PO</em>4$

    • d. Silicon Dioxide: $SiO_2$

    • e. Dinitrogen Tetroxide: $N<em>2O</em>4$

    • f. Ammonium Carbonate: $(NH<em>4)</em>2CO_3$

27. Compound Naming: This is like giving special names to different groups of atoms based on specific rules.

    • a. CrCl₃: Chromium(III) Chloride

    • b. Cu₂CO₃: Copper(I) Carbonate

    • c. AsCl₅: Arsenic Pentachloride

    • d. MgSO₄: Magnesium Sulfate

    • e. P₄O₆: Tetraphosphorus Hexoxide

    • f. NaClO₃: Sodium Chlorate

28. Lewis Structures: Draw and analyze for: More pictures of atoms holding hands!

    • a. BeCl₂: Beryllium in the middle, linked to two Chlorine atoms, in a straight line.

    • b. AlCl₃: Aluminum in the middle, linked to three Chlorine atoms, like a flat triangle.

    • c. CF₄: Carbon in the middle, linked to four Fluorine atoms, like a pyramid with three legs and one pointing up.

    • d. H₂O: Oxygen in the middle, linked to two Hydrogen atoms, but it's bent like a boomerang because Oxygen has extra electron pairs.

    • e. NH₃: Nitrogen in the middle, linked to three Hydrogen atoms, like a small pyramid because Nitrogen has one extra electron pair.

29. Balanced Chemical Equations: When chemicals mix, they don't lose any atoms, they just rearrange! So, a 'balanced equation' is like making sure you have the same number of LEGO bricks before and after you build something new.

    • When solid sodium chlorate absorbs energy, it produces solid sodium chloride and oxygen gas:

      • $2 NaClO<em>3(s) \rightarrow 2 NaCl(s) + 3 O</em>2(g)$

    • Barium oxide reacts with carbon dioxide to produce barium carbonate:

      • $BaO(s) + CO<em>2(g) \rightarrow BaCO</em>3(s)$

30. Law of Conservation of Mass: This is a big rule: in any chemical change, you can't create new stuff out of nothing, and you can't make stuff disappear! The total 'weight' of everything before the change must be the same as after.

    • This law states that matter cannot be created or destroyed in a chemical reaction and is demonstrated through balanced equations where the total mass of reactants equals the total mass of products.

31. Balanced Reaction Equations: Classify and balance: Let's organize these reactions and make sure we have the right number of LEGO bricks!

    • a. $\text{Cu} + \text{MgSO}<em>4 \rightarrow \text{CuSO}</em>4 + \text{Mg}$ (SR) (This is already balanced. SR means Single Replacement: one atom swaps with another similar atom in a compound).

    • b. $C<em>5H</em>{12} + O<em>2 \rightarrow CO</em>2 + H<em>2O$ (C) (This needs balancing: $C</em>5H<em>{12} + 8 O</em>2 \rightarrow 5 CO<em>2 + 6 H</em>2O$. C means Combustion: something burning with oxygen).

    • c. $Fe<em>2O</em>3 \rightarrow Fe + O<em>2$ (D) (This needs balancing: $2 Fe</em>2O<em>3 \rightarrow 4 Fe + 3 O</em>2$. D means Decomposition: one thing breaking into smaller pieces).

    • d. $Ca(NO<em>3)</em>2 + Na<em>2SO</em>4 \rightarrow CaSO<em>4 + NaNO</em>3$ (DR) (This needs balancing: $Ca(NO<em>3)</em>2 + Na<em>2SO</em>4 \rightarrow CaSO<em>4 + 2 NaNO</em>3$. DR means Double Replacement: two pairs of atoms swap partners).

32. Definition of Precipitate: Imagine mixing two clear liquids, and suddenly, tiny solid crumbs appear and fall to the bottom. Those crumbs are a 'precipitate'!

    • A precipitate is an insoluble solid formed in a solution during a chemical reaction.

33. Chemical Reaction Evidence: How can you tell if a real chemical change (like baking a cake, not just melting ice) happened? Look for these clues!

    • Four pieces of evidence for a chemical reaction include:

      • Change in color (like when a banana turns brown)

      • Formation of a gas/bubbles (like fizzing soda)

      • Formation of a precipitate (like those solid crumbs appearing)

      • Change in temperature or energy (like hand warmers getting hot or ice packs getting cold)

34. Reaction Type Identification: This question refers to an image (which I can't see!). But if you saw a picture of a reaction, you'd try to figure out if it was things joining together, breaking apart, or swapping partners.

35. Variables in Reaction Example: Imagine a balloon filled with air. What happens if you leave it in a hot car? The heat makes the air molecules move super fast, they push harder on the balloon walls, and POP!

    • A balloon pops in a hot car on a summer day due to increased temperature leading to increased gas pressure, resulting in volume expansion until the balloon bursts.

36. Effect of Adding Solvent: Imagine you have a glass of super sugary water (saturated solution). If you add more plain water (solvent), the sugar water tastes less sweet (less concentrated), but you haven't changed how much sugar can dissolve in the original amount of water at that temperature.

    • Adding more solvent to a saturated solution decreases the concentration of solute but does not change the amount of solute that can dissolve at a given temperature.

37. Factors Affecting Solubility: How can you get something to dissolve better or faster?

    • Temperature: For most solid stuff, making the water hotter usually helps more of it dissolve.

    • Particle Size: If you have tiny sugar crystals instead of big lumps, they dissolve faster because more of their surface touches the water.

    • Shaking: Stirring or shaking the mixture makes the stuff dissolve faster too!

38. Acid/Base Characteristics: Acids and bases have special traits. Acids are like lemons, and bases are like soap!

    • a. Sour taste: Acid (like lemons!)

    • b. Reacts with metals: Acid (acids can eat away at some metals)

    • c. Corrosive: Both (both can be dangerous and hurt things)

    • d. Feels slippery: Base (like soap!)

    • e. Turns blue litmus paper red: Acid (a special paper test!)

39. Acids and Bases Definitions (Arrhenius): This is one way scientists describe acids and bases, focusing on what they put into water.

    • Acids: Substances that, when you put them in water, make more special positive pieces called 'hydrogen ions' ($H^+$).

    • Bases: Substances that, when you put them in water, make more special negative pieces called 'hydroxide ions' ($OH^-$).

40. Effect of Adding Water to Acid (pH 3.0): If you have a very sour lemon drink (acid with pH 3.0) and add lots of plain water, it will taste less sour (less acidic). The 'pH' number will go up, closer to 7 (which is plain water).

    • When water is added to an acid, the concentration of hydrogen ions decreases, thereby increasing the pH closer to neutral (pH 7).

41. Temperature and Kinetic Energy Relationship: Remember the balloon in the hot car? The hotter something is, the faster its tiny parts (particles) jiggle and move around!

    • The average kinetic energy of particles in a substance increases with temperature, leading to increased movement.

42. Electron Dot Diagram for Group 5 Element: This is a drawing of an atom's outer 'kids' (valence electrons) as dots around its symbol. A Group 5 element has 5 outer kids.

    • Draw for the element (example: phosphorus, P): So, you'd draw 'P' with five dots around it, usually two together and three separate. Example: $. \dot{\text{P}} :$

43. Chemical Symbol in Electron Dot Diagram: In those dot drawings, the big letter in the middle is like the brain and body of the atom, holding all the inner kids and parents. The dots are just the outermost kids.

    • Represents the element's nucleus and core electrons. Specific representation needed according to the element in question.

44. Charles’ Law Constant Variables: This law talks about how the size (volume) of a gas changes with its temperature, when you don't squeeze it (pressure stays the same). So, if you heat a gas, it gets bigger.

    • In Charles' Law, pressure is constant while volume and temperature relate as $\frac{V<em>1}{T</em>1} =\frac{V<em>2}{T</em>2}$ (Volume divided by Temperature stays the same).

45. Effect of Pressure Increase: If you squeeze a balloon really hard (increase pressure), what happens to its size? It gets smaller!

    • If pressure is increased, then volume must decrease.

46. State of Matter Description: What's special about solid things, like an ice cube? Its tiny parts are packed super close and don't jiggle much at all!