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How does an ion form?
Atoms have protons (positive) and electrons (negative). Normally, they’re balanced, so the atom is neutral.
• Losing electrons makes it positive (cation).
• Gaining electrons makes it negative (anion).
Electrons lost or gained?
Look at the charge of the ion:
• Negative charge means it gained electrons.
• Positive charge means it lost electrons.
Examples:
• Br⁻ is negative → it gained 1 electron.
• Na⁺ is positive → it lost 1 electron.
Ionic or molecular compounds?
• Ionic: Formed when a metal and a non-metal combine. Metals lose electrons, non-metals gain them.
• Molecular: Formed when two non-metals share electrons.
Graph and decomposition questions.
a. The graph shows all samples decompose into the same ratio of gas and powder. That means they are the same material.
b. This shows the law of conservation of mass: the mass of the parts equals the mass of the whole.
c. From the graph, every 6.2 g of powder produces 3.8 g of gas.
51. How to count atoms in a molecule?
Look at the numbers in the formula. For example:
• C₆H₈O₆ → 6 carbons, 8 hydrogens, 6 oxygens.
• NH₄NO₃ → 2 nitrogens, 4 hydrogens, 3 oxygens.
52. How do you know if a compound is ionic or molecular?
• Ionic compounds have high melting points because of strong bonds.
• Molecular compounds have lower melting points.
Net charge of ionic compounds?
Always 0, because the positive and negative charges balance out.
Transition metal charge?
The formula tells you: match the metal’s charge with the negative charges in the compound.
60. When to use parentheses?
Use them for groups of atoms (polyatomic ions) if there’s more than one. Example:
• In Mg(NO₃)₂, the ₂ shows there are 2 nitrate groups (NO₃).
61. Writing formulas
• Write the metal first, then the non-metal or group. Use subscripts for how many of each ion you need.
Example:
• Calcium carbonate: Calcium is Ca²⁺, carbonate is CO₃²⁻ → Formula: CaCO₃.
Prefixes for molecular compounds
Prefixes tell you how many atoms are in the formula:
• Mono = 1, Di = 2, Tri = 3, Tetra = 4, etc.
Example:
• Carbon tetrachloride (CCl₄): Tetra- means 4 chlorines.
How to name acids?
• If the formula has just H and one non-metal: Hydro- + -ic acid.
Example: HCl → Hydrochloric acid.
• If it has oxygen:
• -ate ion → -ic acid (e.g., HNO₃ → Nitric acid).
• -ite ion → -ous acid (e.g., H₂SO₃ → Sulfurous acid).
How I got compound formulas or names:
1. Look at the ion charges: Match positive and negative charges. Example:
• Potassium permanganate: Potassium is K⁺, permanganate is MnO₄⁻ → Formula: KMnO₄.
2. For molecular compounds, use prefixes to tell how many atoms.
• Dichlorine heptoxide: Di- means 2, hept- means 7 → Formula: Cl₂O₇.
69. Naming or writing formulas for substances:
• Look at the elements or polyatomic ions in the formula. For example:
• NaClO₃: Sodium + chlorate ion → Sodium chlorate.
• HgF₂: Mercury(II) fluoride because it has 2 fluorines.
Percentage and production questions:
a. Lime percentage: Find its share of the total production by dividing and multiplying by 100:
.
b. Diatomic gases (N₂, O₂, Cl₂) are molecules made of two atoms. Add their amounts: 26.9 + 17.7 + 10.3 = 55.1 billion kg.
c. Three acids’ percentage: Add their amounts and divide by the total:
.
Sure, I can explain how I determined the names for each of these compounds:
1. Na2S: Sodium sulfide
- Na is sodium, and S is sulfur. The compound is composed of two sodium ions and one sulfide ion.
2. PbSO4: Lead (II) sulfate
- Pb is lead, and SO4 is the sulfate ion. The (II) indicates that lead is in the +2 oxidation state.
3. N2O4: Dinitrogen tetroxide
- N2 is dinitrogen, and O4 is tetroxide. The prefixes "di-" and "tetra-" denote the number of nitrogen and oxygen atoms, respectively.
4. HCl: Hydrochloric acid
- H is hydrogen, and Cl is chlorine. In aqueous solution, it is known as hydrochloric acid.
5. Fe(OH)2: Iron (II) hydroxide
- Fe is iron, and OH is the hydroxide ion. The (II) indicates that iron is in the +2 oxidation state.
6. Cl2O: Dichlorine monoxide
- Cl2 is dichlorine, and O is monoxide. The prefix "di-" denotes the number of chlorine atoms.
7. KClO3: Potassium chlorate
- K is potassium, and ClO3 is the chlorate ion.
8. C2O3: Dicarbon trioxide
- C2 is dicarbon, and O3 is trioxide. The prefixes "di-" and "tri-" denote the number of carbon and oxygen atoms, respectively.
9. ZnF2: Zinc fluoride
- Zn is zinc, and F is fluoride. The compound is composed of one zinc ion and two fluoride ions.
10. Ca(C2H3O2)2: Calcium acetate
- Ca is calcium, and C2H3O2 is the acetate ion. The compound is composed of one calcium ion and two acetate ions.
11. KOH: Potassium hydroxide
- K is potassium, and OH is the hydroxide ion.
12. Ni(MnO4)2: Nickel (II) permanganate
- Ni is nickel, and MnO4 is the permanganate ion. The (II) indicates that nickel is in the +2 oxidation state.
13. (NH4)3PO4: Ammonium phosphate
- NH4 is the ammonium ion, and PO4 is the phosphate ion. The compound is composed of three ammonium ions and one phosphate ion.
14. CdCrO4: Cadmium chromate
- Cd is cadmium, and CrO4 is the chromate ion.
15. Ca(IO3)2: Calcium iodate
- Ca is calcium, and IO3 is the iodate ion. The compound is composed of one calcium ion and two iodate ions.
16. Sn(C2O4)2: Tin (IV) oxalate
- Sn is tin, and C2O4 is the oxalate ion. The (IV) indicates that tin is in the +4 oxidation state.
17. AgClO: Silver hypochlorite
- Ag is silver, and ClO is the hypochlorite ion.
18. NaHCO3: Sodium bicarbonate
- Na is sodium, and HCO3 is the bicarbonate ion.
19. Li2CO3: Lithium carbonate
- Li is lithium, and CO3 is the carbonate ion. The compound is composed of two lithium ions and one carbonate ion.
20. HC2H3O2: Acetic acid
- H is hydrogen, and C2H3O2 is the acetate ion. In its molecular form, it is known as acetic acid.
Let me know if you have any more questions!
1. Beryllium acetate: Beryllium (Be) has a +2 charge, and acetate (C2H3O2) has a -1 charge. Therefore, the formula is Be(C2H3O2)2.
2. Trinitrogen pentoxide: This compound consists of three nitrogen (N) atoms and five oxygen (O) atoms. Therefore, the formula is N3O5.
3. Tin (II) chloride: Tin (Sn) with a +2 charge and chloride (Cl) with a -1 charge. Therefore, the formula is SnCl2.
4. Ammonium oxide: Ammonium (NH4) has a +1 charge, and oxide (O) has a -2 charge. Therefore, the formula is (NH4)2O.
5. Barium nitrate: Barium (Ba) has a +2 charge, and nitrate (NO3) has a -1 charge. Therefore, the formula is Ba(NO3)2.
6. Sodium chlorite: Sodium (Na) has a +1 charge, and chlorite (ClO2) has a -1 charge. Therefore, the formula is NaClO2.
7. Iodine: Iodine is a diatomic molecule in its elemental form. Therefore, the formula is I2.
8. Carbon tetrafluoride: This compound consists of one carbon (C) atom and four fluorine (F) atoms. Therefore, the formula is CF4.
9. Silver oxalate: Silver (Ag) has a +1 charge, and oxalate (C2O4) has a -2 charge. Therefore, the formula is Ag2C2O4.
10. Lead (II) sulfide: Lead (Pb) with a +2 charge and sulfide (S) with a -2 charge. Therefore, the formula is PbS.
11. Lead (II) hydrogen sulfide: This is not a standard compound, but if you mean lead (II) hydrosulfide, it would be Pb(HS)2, but this is rarely used.
12. Lead (II) hydrogen sulfate: Lead (Pb) with a +2 charge and hydrogen sulfate (HSO4) with a -1 charge. Therefore, the formula is Pb(HSO4)2.
13. Lead (II) sulfate: Lead (Pb) with a +2 charge and sulfate (SO4) with a -2 charge. Therefore, the formula is PbSO4.
14. Lead (II) sulfite: Lead (Pb) with a +2 charge and sulfite (SO3) with a -2 charge. Therefore, the formula is PbSO3.
15. Sulfuric acid: Consists of hydrogen (H), sulfur (S), and oxygen (O). The formula is H2SO4.
16. Nickel (II) cyanide: Nickel (Ni) with a +2 charge and cyanide (CN) with a -1 charge. Therefore, the formula is Ni(CN)2.
17. Cobalt (II) silicate: Cobalt (Co) with a +2 charge and silicate (SiO4) with a -4 charge. Therefore, the formula is Co2SiO4.
18. Copper (I) hydrogen phosphate: Copper (Cu) with a +1 charge and hydrogen phosphate (HPO4) with a -2 charge. Therefore, the formula is Cu2HPO4.
19. Disulfur tribromide: This compound consists of two sulfur (S) atoms and three bromine (Br) atoms. Therefore, the formula is S2Br3.
20. Nitric acid: Consists of hydrogen (H), nitrogen (N), and oxygen (O). The formula is HNO3.