Practice Problems & Chapter 2 Atoms and Elements

Lecture 2.2.21 Practice Problems 6.5 g = mg 6.5 g * (1000 mg / 1 g) = 6500 mg or 6.5 g * (1 mg / 0.001 g) = 6500 mg 6.5 mg = g 6.5 mg * (1 g / 1000 mg) = 0.0065 g 60 mi/hr to km/sec 1 mi = 1.6 km 60 mi/hr * (1.6 km / 1 mi) * (1 hr / 60 min) * (1 min / 60 sec) = 0.026 km/sec (60 * 1.6 / 60 / 60) = 0.026 Sig Fig Rules Rule 1: Multiplication and Division 2.5423 * 1.2 = 3.05076 (use the least amount of sig figs 2) Answer should be 3.0 or 3.1 Example: 2.32987 / 1.23 = 1.89420325203 Section 2.1 All mater is made up of atoms. By understanding the nature of atoms, we can predict how observable matter behaves. Atom: A fundamental particle of matter atomos, a Greek term for "Indivisible" Different atoms can bond to one another in fixed proportions to form chemical compounds. Atomic Structure: The combination of all the particles that compose an atom, their relationships to one another, and their locations within the atom Electrons Small, negatively charged particles located in shells surrounding an atom's nucICUS. Nucleus: The extremely small, dense center of the atom in which the atom's positive charge is localized. Quantum Shells: The orbits of electrons at fixed distances from the nucleus, as described in the Bohr (Niels Bohr) model of the atom. Section 2.2 • The negative charge of electrons in quantum shells surrounding the nucleus is balanced by the positive charge of the nucleus itself. This positive charge is provided by Protons. ↳ Protons: A positevery charged particie found within the nucleus of the atom. Atomic number: The number of protons in the nucleus of an atom. Element ALAR come aromiC Neutron: A nuclear particle that carries no electric charge→ They have no effect on the atomic number, but contribute to the mass and weight of the atom. Protons: por p+ Electrons e ore- Neutrons: nor n° Mass number: The combined number of protons and neutrons in the nucleus of an atom. Mass # Atomic H Powers of ten: simply multiplies of the number to expressed as exponents of the number 10. Protons and neutrons are each about 1 x 10-15 meters in diameter, or a millionth of a billionth of a meter. This is about 200 million times bigger than the smallest objects visible by high-power, light microscopes. Electrons are far smaller than even protons and neutrons. Section 4.1 Chapter WOLCS Energy The capacity to perform work. Potential energy: stored energy due to an object's position in space or due to the composition of a substance. kinetic energy: The energy of motion. Law of conservation of energy: A natural law recognizing that energy can neither be created nor destroyed but can only be Section 4.1 Energy The capacity to perform work. Potential energy: stored energy due to an object's position in space or due to the composition of a substance. kinetic energy: The energy of motion. Law of conservation of energy: A natural law recognizing that energy can neither be created nor destroyed but can only be converted from one form to another. Heat: The energy that flows from a warmer body to a cooler one. The first and second laws of thermodynamics: - The law of conservation of energy. Entropy: A measure of the disorder or randomness of the positions of a collection of atoms, lons, or molecules. Energy exists in many forms chemical, electrical, biological, thermal, and more-but energy itself is usually described in terms Of its equivalent in heat. ↳ Calorie heat/energy source 1000 calories (cal) = I kilocalorie (kcal) = I Calorie ccal) Joule: A unit of energy relationship between work and heat ↳ I joule (J) = 0.24 calories