lecture 1 - states of matter Flashcards
What is matter?
Matter is anything with mass and volume (occupies space).
How is matter classified by physical state?
Matter is classified into three physical states: solid, liquid, and gas.
What are the characteristics of a solid?
A solid has a fixed volume and shape; atoms are arranged in a regular pattern.
What are the characteristics of a liquid?
A liquid has a fixed volume but no fixed shape; particles can slide past one another.
What are the characteristics of a gas?
A gas has neither fixed shape nor volume; particles move freely in random directions.
How is matter classified by composition?
Matter is classified into elements, compounds, and mixtures.
What is an element?
An element is a pure substance consisting of only one type of atom (e.g., Fe, O).
What is a compound?
A compound is a substance formed from two or more elements bonded together (e.g., H₂O).
What is a mixture?
A mixture is a physical combination of two or more substances without chemical bonding.
What is an atom?
An atom is the smallest building block of matter, electrically neutral.
What is the atomic number?
The atomic number is the number of protons (equals electrons in a neutral atom).
What is the mass number?
The mass number is the sum of protons and neutrons.
What are isotopes?
Isotopes are variants of an element with the same number of protons but different neutrons.
What is a molecule?
A molecule is a group of two or more atoms bonded covalently.
What is the difference between molecules and compounds?
Molecules can be of the same element (e.g., O₂), but compounds must have different elements (e.g., CO₂).
What is the particle behavior in solids?
In solids, particles are tightly packed in a fixed arrangement with minimal movement, primarily vibrational.
What is the particle behavior in liquids?
In liquids, particles are close but can move past each other, maintaining a fixed volume and taking the shape of the container.
What is the particle behavior in gases?
In gases, particles are far apart with high energy, having no fixed volume or shape.
What factors affect the state of matter?
Temperature and pressure influence particle motion and arrangement, determining the state of matter.
Why do atoms bond?
Atoms bond to achieve a more stable, lower-energy state.
What are valence electrons?
Valence electrons are key to bonding.
What do chemical bonds do?
Chemical bonds lower the potential energy between interacting atoms.
What is an ion?
An ion is a charged particle formed when atoms lose or gain electrons (e.g., Na⁺, Cl⁻).
What is a chemical formula?
A chemical formula represents types and numbers of atoms in a compound (e.g., NH₃ for ammonia with 1 nitrogen and 3 hydrogen atoms).
What are the three physical states of matter?
• Solid: Fixed shape and volume, tightly packed particles.
• Liquid: Fixed volume, no fixed shape, particles move past each other.
• Gas: No fixed shape or volume, particles move freely.
What determines the state of matter?
Temperature and pressure, which affect particle motion and arrangement.
Define an atom.
The smallest unit of an element, consisting of protons and neutrons in the nucleus, and electrons orbiting the nucleus.
What is the difference between an atomic number and mass number?
• Atomic Number: Number of protons (or electrons in a neutral atom).
• Mass Number: Total number of protons and neutrons.
What is an isotope?
Atoms of the same element with the same number of protons but different numbers of neutrons.
Define a molecule.
A neutral group of two or more atoms bonded covalently.
Can all molecules be compounds?
No. Molecules can consist of the same element (e.g., O₂), but compounds must have different elements (e.g., H₂O).
What are ions?
Atoms or molecules that become charged by gaining or losing electrons (e.g., Na⁺, Cl⁻).
What is a chemical formula?
A representation of the types and numbers of atoms in a compound (e.g., NH₃ for ammonia).
Explain the use of brackets in chemical formulas with an example.
• Brackets indicate grouping in formulas.
• Example: Mg(OH)₂ means one magnesium, two oxygen, and two hydrogen atoms.
Name and symbol of the first five elements in the periodic table?
- Hydrogen (H)
- Helium (He)
- Lithium (Li)
- Beryllium (Be)
- Boron (B)
Why do atoms form chemical bonds?
To increase stability and lower potential energy.
What are valence electrons?
Electrons in the outermost shell of an atom that participate in bonding.
