💥 Sodium Goes BOOM
Oxygen-16 has an atomic number of 8. Determine its number of protons, neutrons, and electrons if it is neutral.
8 protons, 8 neutrons, and 8 electrons
Atomic number gives protons. A neutral atom has equal protons and electrons. Mass number 16 minus 8 protons gives 8 neutrons.
Oxygen has 6 valence electrons. How many covalent bonds does it typically form in our model, and why?
Two covalent bonds
Oxygen needs access to two more electrons to model a stable outer energy level of eight.
Identify the solute and solvent in saltwater
Solute = salt
solvent = water
When water sticks to other water molecules, it is using __________.
Cohesion
In the equation 2H2 + O2 = 2H2O,
identify the reactants and products.
2H2 and O2 are reactants
2H2O is the product
Carbon-12 and carbon-14 are both carbon. What particle differs, and why do they remain the same element?
They have different numbers of neutrons but the same number of protons.
Both have 6 protons, which identifies carbon. The different neutron numbers make them isotopes.
Classify O₂, H₂O, and NaCl as molecules, compounds, or both. Include the main bond type in each.
O₂: molecule, covalent.
H₂O: molecule and compound, covalent.
NaCl: compound, ionic.
A molecule contains covalently bonded atoms. A compound contains two or more different elements.
Solution A has pH 3 and Solution B has pH 5. Which is more acidic, and which ions are more present?
Solution A with more Hydrogen (H+) ions.
Oil separates from water. What does this evidence suggest about oil, and why does separation occur?
Oil is nonpolar and hydrophobic.
Polar water molecules interact strongly with one another, while nonpolar oil cannot form equally favorable interactions with water.
A clear sports drink contains water, ions, sugar, flavoring, and acids. Why is it a solution rather than a new compound?
Its components are evenly distributed and physically mixed.
A solution is a homogeneous mixture, not a single chemically combined compound.
A sodium particle has 11 protons and 10 electrons. Identify its charge and explain how it differs from a neutral sodium atom.
It has a +1 charge and is Na⁺.
It has one more proton than electron. Neutral sodium has 11 electrons, while Na⁺ has lost one electron.
Model the formation of NaCl. Identify the electron movement, the charge of each ion, and what holds the ions together.
Na transfers one electron to Cl, producing Na⁺ and Cl⁻. Their opposite charges attract in an ionic bond.
What is a solution?
A mixture in which undissolved substances do not settle out.
The 2 hydrogen atoms connect with the oxygen atom WITHIN a water molecule by using these bonds.
covalent
Why can sodium metal react violently with water while the sodium listed on a sports-drink label does not?
Sodium metal contains neutral sodium atoms. The drink contains dissolved Na⁺ ions that have already lost an electron.
An unknown particle has atomic number 15, mass number 31, and 18 electrons. Determine its protons, neutrons, and net charge.
15 protons, 16 neutrons, and a 3− charge.
31 − 15 = 16 neutrons. Three extra electrons give the particle a net charge of 3−.
Explain the octet rule and how many electrons fit in each energy shell.
The octet rule states that an atom stabilizes when the outermost orbitals are filled with electrons. The first orbital can fill up to 2 electrons, and the subsequent orbitals can fill up to 8 electrons.
When pure water dissociates, it produces equal numbers of these two ions.
H⁺ (hydrogen) and OH⁻ (hydroxide) ions
Why do hydrophobic substances not mix well with water?
Nonpolar substances do not have partial charges
Salt and sugar dissolve in water, but oil separates. Explain all three outcomes using polarity and particle interactions.
Water surrounds salt ions and interacts with polar regions of sugar. Nonpolar oil lacks compatible partial charges and separates.
Evaluate this claim: “Electrons always equals protons in every atom, and electrons + protons = mass number."
Electrons are only equal to protons in a neutral atom (atoms without a charge). Protons + neutrons = mass number.
Correct this statement: “Hydrogen bonds connect each hydrogen to oxygen inside one water molecule, so they are as strong as covalent bonds.”
Covalent bonds connect H to O within one molecule. Hydrogen bonds attract partial charges on neighboring water molecules and are weaker individually.
Describe the pH scale. Include:
-- the range
-- what is neutral, basic and acidic
-- which ions are present
It ranges from 0-14 with 7 being neutral. Anything less than 7 is more acidic with more Hydrogen (H+) ions present. Anything greater than 7 is basic with more Hydroxide (OH-) ions present.
Explain why water is a polar molecule, and how it can dissolve salt but not oil.
Water has an uneven distribution of electrons with oxygen being very electronegative. This gives it partial charges which attract and surround salt’s ions. Oil is nonpolar and cannot form similarly favorable attractions with water, so it separates.
Build a causal explanation: How do electron arrangement, bonding, and water's polarity allow a sports drink to remain one stable liquid?
Electron arrangements determine charges and bonding. Polar water attracts ions and polar solutes, surrounds them, and distributes them throughout the mixture.