Transcript Study Guide
Study Guide Study Guide Dalton’s model of the atom: Study Guide Dalton’s model of the atom: Hard, round, and unbreakable like a billiard ball. Study Guide Thompson’s model of the atom: Study Guide Thompson’s model of the atom: Small, negatively charged electrons scattered like chocolate chips throughout a positively charged cookie. Study Guide Rutherford’s model of the atom: Study Guide Rutherford’s model of the atom: Mostly empty space with a small, hard, positive nucleus surrounded by even smaller negatively charged electrons. How did Thompson figure out that electrons were smaller than atoms? How did Thompson figure out that electrons were smaller than atoms? •He used a cathode ray tube •Shot a beam of electrons •Deflected the beam with a magnet •Knew how hard the magnet pulled •Saw how far beam was defected •Calculated mass from those numbers How did Rutherford figure out that the nucleus was small and hard? How did Rutherford figure out that the nucleus was small and hard? •Shot alpha particles at gold foil •Most particles went right through •Therefore atoms must be mostly empty space •A few particles bounced back •Therefore atoms must have something small and hard in the middle. Study Guide Atomic number: Study Guide Atomic number: Number of protons in an element. Study Guide Atomic mass: Study Guide Atomic mass: Average mass of atoms of an element. (Not necessarily a whole number.) Study Guide AMU: Study Guide AMU: Atomic mass unit. 1/12 the mass of a carbon atom. Study Guide Mass number: Study Guide Mass number: The exact number of protons + neutrons in a specific atom. (Must be a whole number.) Study Guide Isotope: Study Guide Isotope: At atom with a different number of neutrons than other atoms of the same element. Study Guide Abundance: Study Guide Abundance: The number of atoms of one isotope ÷ the total number of atoms of that element. Study Guide Nuclear reaction: Study Guide Nuclear reaction: The nucleus of an atom gains or loses protons and becomes a different element. Study Guide Radioactive decay: Study Guide Radioactive decay: One kind of nuclear reaction. The nucleus emits alpha or beta particles and sometimes gamma rays. Study Guide Alpha particle: Study Guide Alpha particle: Two protons and two neutrons. It is the same thing as a helium nucleus, with a charge of +2. Study Guide Beta particle: Study Guide Beta particle: An electron, with a charge of -1. Study Guide Gamma ray: Pure energy with no mass and no charge. How can one element turn into a different element? How can one element turn into a different element? •Only by changing the number of protons. •Emitting an alpha particle decreases atomic number by two. •Emitting a beta particle increases atomic number by one.