Presentation on theme: "Chapter 4: Atomic Structure"— Presentation transcript:
1 Chapter 4: Atomic Structure 4.1: Studying Atoms4.2: The Structure of an Atom4.3: Modern Atomic Theory
2 4.1: Studying AtomsGreeksDaltonThomsonRutherfordAtomic Model
3 Ancient Greek Models of Atoms Democritus believed that all matter consisted of extremely small particles that could not be divided.
4 Ancient Greek Models of Atoms Democritus called these particles atoms from the Greek word atomos, which means “uncut” or “indivisible.”He thought there were different types of atoms with specific sets of properties
5 AristotleThought that all substances were built up from only four elements.
6 Dalton’s Atomic Theory Proposed the theory that all matter is made up of individual particles called atoms, which cannot be divided.Compounds contain atoms of more than on element.In a particular compound, atoms of different elements always combine in the same way.
7 Dalton’s ExperimentThe ratio of the masses of the elements in the compound is always the same.A 100 gram sample of magnesium combines with 65.8 grams of oxygen.A 10 gram sample of magnesium combines with 6.58 grams of oxygen.
8 Dalton’s ModelThe elements are pictured as solid spheres.
15 Rutherford’s ModelAll of an atom’s positive charge is concentrated in its nucleus.The nucleus is a dense, positively charged mass located in the center of the atom.Pretending to be Alpha Particles Mv.
16 4.2:Structure of an AtomProtons, electrons, and neutrons are subatomic particles.Because these particles are even smaller than an atom, they are called subatomic particles.These three types of particles are arranged in an atom as shown below.
17 What makes one element different from another if? All protons are the same.All electrons are the same.All neutrons are the same.
18 ProtonsThe number of protons distinguishes an atom of one element from the atom of another element.All atoms of the same element will have the same number of protons, and atoms of different elements will have different numbers of protons.
20 Properties of Subatomic Particles Protons, electrons, and neutrons can be distinguished by mass, charge, and location in an atom.
21 Atomic Number The number of protons in an atom of that element. Because the number of protons in an atom remains the same during physical and chemical changes, we can refer to each element by the number of protons its atoms contain. This unique number is called the atomic number.
22 # protons = # electrons Atomic Number Because atoms have an overall neutral charge, atoms have an equal number of protons & electrons.# protons = # electrons
23 Mass Numberthe sum of the protons and neutrons in the nucleus of that atom.
24 IsotopesIsotopesatoms of the same element that have different numbers of neutrons and different mass numbers.