Chem
What is an isotope?
An isotope is a variant of an element that has the same number of protons (same atomic number) but a different number of neutrons, leading to different mass numbers.
Describe the difference between a cation and an anion.
Cation: A positively charged ion formed when an atom loses electrons. Example: Na⁺ (sodium ion).
Anion: A negatively charged ion formed when an atom gains electrons.
What is an ionic bond, and how does it form?
An ionic bond is a type of chemical bond that forms through the transfer of electrons from one atom to another. It typically occurs between a metal (which loses electrons to become a cation) and a nonmetal (which gains electrons to become an anion).
Finish the lyric: "When you first left me, I didn't know what to say ....."
"I never been on my own that way."
Why are noble gases considered unreactive compared to other elements?
Noble gases have a full valence shell of electrons, making them chemically stable and unlikely to gain, lose, or share electrons.
Finish the lyric: "Two lovers entwined pass me by ......"
"And Heaven knows, I'm miserable now."
What are the main differences between metals, nonmetals, and metalloids?
Metals: Good conductors of heat and electricity, malleable, ductile, and usually solid at room temperature.
Nonmetals: Poor conductors, brittle, and may exist as solids, liquids, or gases.
Metalloids: Exhibit properties of both metals and nonmetals, depending on conditions.
Finish the lyric: "Vamos para arriba, no hay ninguna prisa ....."
"Solo quiero sentir tus labios y que seas mía"
Finish the lyric: "Come on, don't leave, it can't be that easy, babe ....."
"If you believe me, I guess I'll get on a plane"
What is the significance of the groups and periods in the periodic table?
Groups (vertical columns): Elements in the same group have similar chemical properties due to the same number of valence electrons.
Periods (horizontal rows): Represent elements with the same number of electron shells.
Explain the difference between atomic number and mass number.
Atomic Number: The number of protons in the nucleus of an atom, which determines the element's identity.
Mass Number: The total number of protons and neutrons in the nucleus of an atom.
How do you determine the chemical formula of an ionic compound formed between two given ions?
Combine the ions in a ratio that neutralizes the total charge. For example, to form a compound with Mg²⁺ and Cl⁻, the formula is MgCl₂ because two chloride ions are needed to balance the charge of one magnesium ion
What is the rule for naming ionic compounds containing transition metals?
The name includes the metal's name followed by its oxidation state in Roman numerals in parentheses.
What are the properties of ionic compounds?
High melting and boiling points.
Soluble in water.
Conduct electricity in molten or aqueous states.
Brittle and crystalline in solid form.
Reading the lyrics provided, who performs this song? "And I smile when I think of all the times we had, On the beach in the winter when the waves were mad."
The Marias
An atom contains 11 protons, 12 neutrons, and 10 electrons. What is its atomic mass?
23
What is an atom, and what are its main components?
An atom is the smallest unit of matter that retains the properties of an element. It is composed of three main subatomic particles: protons, neutrons, and electrons.
Name the following ionic compound: Fe₂O₃
Iron(III) oxide
If an atom of magnesium loses two electrons, what is the resulting ion, and how many protons and electrons does it have?
Magnesium loses two electrons, forming a Mg²⁺ ion.
Number of Protons = 12 (unchanged)
Number of Electrons = 12 - 2 = 10 electrons.
An element has 17 protons and 18 neutrons. Determine its atomic number and mass number, and identify the element.
Atomic Number = Number of Protons = 17
Mass Number = Protons + Neutrons = 17 + 18 = 35
The element is chlorine (Cl).
Calculate the number of neutrons in an atom with an atomic number of 15 and a mass number of 31.
16
If the abundance of two isotopes of an element is 70% for isotope A (atomic mass = 62 u) and 30% for isotope B (atomic mass = 64 u), calculate the average atomic mass of the element.
62.6 amu
Determine the formula for an ionic compound formed between aluminum ions (Al³⁺) and sulfate ions (SO₄²⁻).
The charges need to balance:
Al³⁺ requires two sulfate ions (SO₄²⁻) to balance the charges.
Formula: Al₂(SO₄)₃.
What is the Bohr Model?
Bohr Model: Proposes that electrons orbit the nucleus in fixed, circular paths called energy levels or shells. Each orbit corresponds to a specific energy.
Calculate the average atomic mass of an element with two isotopes: one isotope with a mass of 10 u and an abundance of 20%, and another isotope with a mass of 11 u and an abundance of 80%.
(10 × 0.20) + (11 × 0.80)
2 + 8.8 = 10.8 u.