![]() ![]() If the atom gains/loses energy, the energy of the electron changes Energy levels- the possible energies that electrons in an atom can have Electrons cannot exist between energy levels They must be in one energy level Each step away from the nucleus represents a gain in energy ***An electron can move from one energy level to another when the atom gains or loses energyģ4 Question: What determines the amount of energy gained/lost when an electron moves between energy levels?ģ5 Answer: The size of the jump between energy levelsįireworks!!! Heat produced by the explosion causes e- to move to higher energy levels When those e- move back to a lower energy level, they emit energy (lose energy). His model focused on the electrons Electrons move in orbits around the nucleus Like planets around the sunģ2 ENERGY LEVELS Each electron in orbit has a specific amount of energy. Stable electron configurationsĢ8 Vocabulary: Energy levels Electron Cloud OrbitalĢ9 BOHR’S MODEL 1885-1962 Danish physicist What is the atomic # of uranium?Ģ7 4.3 MODERN ATOMIC THEORY Key Concepts:Įlectrons move from energy levels when they gains/loses energy The electron cloud model describes the possible locations of electrons around the nucleus An electron cloud is a good approximation of how electrons behave in orbitals. Uranium-235 (mass of 235) has 143 neutrons in the nucleus. Uranium-238 has a mass number of 238 with 146 neutrons in the nucleus. You can also refer to atoms by using the mass number and the name of the element. The composition of any atom can be represented in shorthand notation using atomic number and mass number The chemical symbol Au appears with two numbers written to its left. But…every atom of a given element does not have the same number of neutrons.Ģ3 Isotopes Isotopes of an element have the same atomic number but different mass numbers because they have different numbers of neutrons. Every atom of a given element does have the same number of protons and electrons. The atomic number of an element also equals the number of electrons in an atom.ġ7 Mass Number Mass Number- the sum of the protons and neutrons in the nucleus of an atom Using the mass number is the only way to find the number of neutronsĢ1 Isotopes Isotopes- atoms of the same element that have different numbers of neutrons and different masses. There is one proton in the nucleus of each and every hydrogen (H) atom…always…no exceptions! Each element has a unique (different) atomic number Atoms of different elements have different numbers of protons.ġ5 Atomic Number Each positive charge in an atom is balanced by a negative charge because atoms are neutral. The atoms of any given element always have the same number of protons. Everything scientists know about the nucleus and subatomic particles is based on how the particles behave.ġ3 Atomic Number Atomic Number- equals the number of protons in an atom Protons, electrons, and neutrons can be distinguished by mass, charge, and location in an atom. If an atom were the size of a football stadium, the nucleus would be about the size of a marble. the nucleus is tiny compared with the atom as a whole. ![]() The protons and neutrons are located in the nucleus The electrons are distributed around the nucleus and occupy almost all the volume of the atom. "For you," the bartender replied "no charge." 10 No chargeġ0 A neutron walked into a bar and asked for the price of a drinkĪ neutron walked into a bar and asked for the price of a drink. 3 Subatomic Particles Protons (Rutherford)- a positively charged subatomic particle in the nucleus Each nucleus must contain at least one particle with a positive charge.Ħ Subatomic Particles Electrons (Thomson)- a negatively charged particle found in the space OUTSIDE the nucleus Each electron has a charge of –1.Ĩ Subatomic Particles Neutrons (Chadwick)- a neutral subatomic particle found in the nucleus Neutrons have a mass almost exactly equal to that of a proton. ![]()
0 Comments
Leave a Reply. |