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Vocabulary/Concept 1. What are elements? 2. What are atoms? 3. What are molecules? 4. Who was the first person to suggest or identity the atom? 5. What are the four parts of an atom? 6. What is a nucleus? 7. What's the difference between protons and neutrons? 8. What makes up the rest of an atom? 9. How many electrons are in each energy shell? 10. What are electrons? 11 . What do electrons and protons have in common? 12. What is the purpose of the periodic table? 13. How is the Periodic Table arranged? 14. What do the periods represent? Definitions/Description/Examples Elements are substances that cannot be separated into simpler substances. Elements are made up of atoms, Atoms are the basic unit of matter that makes up everything around us. It's the "stuff". Molecules are a combination of two or more atoms. Ex: A water molecule includes two hydrogen atoms and one oxygen atom. Democritus — Greek philosopher who first used the word atom to describe the smallest thing found in the universe and believed that if you continued breaking down an object into smaller and smaller pieces, you would eventually end up with an atom. The word atom means "cannot be destroyed". Protons, Neutrons, and Electrons The nucleus is the center part of an atom, which contains protons and neutrons. The nucleus takes up only a very small fraction of an atom's space, but almost 100 percent of its mass (comes from the protons and neutrons-roughly the same size and weight) Protons=positive charge Neutrons=no charge The rest of an atom is mostly empty space called energy clouds where electrons are found. Within the energy cloud, electrons move in energy levels called shells-Electrons in the outermost energy shell interact and bond with other atoms. Starting from the nucleus, the shells can hold 2, 8, 18, and then 32 electrons Electrons are smaller than you can imagine and have almost no mass. They weigh about 2000 times less than protons and neutrons and have a negative charge. Usually an atom has the same number of electrons and protons, so their charges balance each other. This makes the atom neutral. Ex: The element Nitrogen has seven protons in its nucleus. This means that it has seven electrons. The atomic number on the Periodic Table is also seven. Properties of elements can be identified or predicted based on its location on the periodic table. 7 horizontal rows called periods and 18 vertical columns called groups or families. AH of the elements in a period have the same number of energy shells. Every element in the top row (the first period) has one shell for tls electrons. All of (he demenis in the second row (the second period) have two shells for their electrons. It goes down the periodic table like that. At this time, the maximum number of electron shells or electron shells for any element is seven. 15, What do the groups or families represent? The elements in a group have the same number of electrons in their outer shell. Every element in the first column (group one) has one electron in its outer shell. Every element on the second column (group two) has two electrons in the outer shell. As you keep counting the columns, you'll know how many electrons are in the outer shell, but there are some exceptions. 16. What are some exceptions? Hydrogen and helium are special elements. Hydrogen can have the talents and electrons of two groups, one and seven. To scientists, hydrogen is sometimes missing an electron, and sometimes it has an extra. Helium is also different from all of the other elements. It can only have two electrons in its outer shell. Even though it only has two, it is still grouped with elements that have eight. 17. What is an atom's atomic number? The atomic number is equal to the number of electrons in an atom. If the atom is neutral, the atomic number is also equal to the number of electrons. The chemical symbol is an abbreviation of an clement. 1 8. What is the chemical symbol of an element? 19. What is the atomic mass? 20. What is the Lewis Dot Diagram? The atomic mass is the amount of "stuff that makes up an atom. The atomic mass is the total mass of an atom's protons, neutrons, and electrons. The Lewis Dot Diagram helps to show the number of valence electrons an atom can hold. Valence electrons are the most important electrons in an atom, which are found in the outer energy level.