Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Atoms: The Building Blocks of Matter Chapter 3 Basic laws of chemical reactions Law of conservation of mass: mass is neither created nor destroyed in ordinary reactions Law of definite proportions: a chemical compound always contains the same elements in exactly the same proportions by mass regardless of the size of the sample or the source of the compound Dalton’s Atomic Theory 1. 2. 3. 4. 5. All matter is composed of extremely small particles called atoms. Atoms of a given element are identical in size, mass, & other properties. Atoms cannot be subdivided, created, or destroyed. Atoms of different elements combine in simple whole number ratios to form chemical compounds. In chemical reactions, atoms are combined, separated, & rearranged. The modern atomic theory has proven that atoms are divisible into smaller particles & that a given element can have atoms with different masses. The Atom Atom: smallest particle of an element that retains the chemical properties of that element Contains 2 parts: Nucleus: located near the center of the atoms Electron cloud: located in rings around the nucleus Subatomic Particles The atom contains 3 basic subatomic particles: Proton: positively charged particle located inside the nucleus Neutron: neutrally charged particle located inside the nucleus Electron: negatively charged particle located in the rings of the electron cloud Atomic & Mass Number atomic number (Z): number of protons in the nucleus of each atom The atomic number identifies an element. mass number: total number of protons & neutrons in the nucleus Scientists use atomic mass units (amu) to measure the mass of atoms. Isotopes All atoms are composed of the same basic particles, but all atoms are not the same. Atoms of different elements have different number of protons. Isotope: atoms of the same element that have different masses Cont’d… Most elements occur naturally as a mixture of isotopes. Average atomic mass: weighted average of the atomic masses of the naturally occurring isotopes of an element Problem Copper is a naturally occurring isotope. It consists of 69.17% copper-63 and 30.83% copper-65. Calculate the average atomic mass of the naturally occurring copper if copper-63 weighs 62.929598 amu and copper-65 weighs 64.927793 amu. The Mole Mol: SI unit for amount of substance Avogadro’s number: number of particles in a mole, 6.02x1023 Molar mass: mass of 1 mole of a pure substance Written in grams/mole (g/mol) Equal to the atomic mass number found on the periodic table Mole Conversions Problems 1. 2. 3. 4. What is the mass in grams of 3.50 mol of the element copper? A chemist produced 11.9 g of aluminum. How many moles of aluminum were produced? How many moles of silver (Ag) are in 3.01x1023 atoms of Ag? What is the mass in grams of 1.20x108 atoms of copper?