Big Idea 5. What do atoms look like? Day 1. Weekly Question

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Beryl Clarke
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1 1 Nearly everything in the universe is made of matter. This paper is made of matter. You are made of matter. Even the air we breathe is made of matter. But what is matter? Matter is anything that has both mass and volume. In other words, matter is any object or substance that is composed of particles and takes up space. The basic building blocks of matter are the elements. An atom is the smallest unit of an element that still has all the properties of that element. Oxygen is an element. Iron is an element. Gold and silver are both elements. There are 117 known elements, which means there are 117 types of atoms. More elements certainly exist, though they have yet to be discovered. A. Write true or false. 1. We know that only 117 elements exist. 2. The smallest unit of an element is an atom. 3. Gold and silver are made of atoms. atom AT-um the smallest unit of an element that contains all the properties of that element elements EL-ih-mentz basic chemical substances from which all matter is made 4. Atoms are the basic building blocks of matter. B. Even though it is invisible, air is composed of matter. In your own words, explain why this is true. C. Fill in the bubble next to the phrase that completes the analogy. Atom is to element as. A matter is to iron B element is to matter C matter is to element D element is to oxygen Evan-Moor Corp. EMC 5016 Week 1 129

2 2 Although an atom is the smallest particle of an element, it is not the smallest particle of matter. Atoms are composed of even smaller particles called protons, neutrons, and electrons. A proton has a positive electric charge. An electron has a negative electric charge. And a neutron has no electric charge. Protons and neutrons are about the same size. Electrons, however, are much smaller. Atoms are identified by the number of protons they contain. For example, all atoms with eight protons are oxygen atoms. All atoms with 26 protons are iron atoms. Many atoms, such as oxygen, have the same number of neutrons as they do protons. Some atoms, such as iron, have more neutrons than protons. Only one kind of atom has fewer neutrons than protons. This is hydrogen, which contains one proton and no neutrons. In any atom, the number of electrons equals the number of protons, which makes the atom electrically neutral. A. Use the vocabulary words and the information in the passage to complete the paragraph. electron ee-lek-trahn with a charge of 1 neutron NOO-trahn with a charge of 0 proton PRO-tahn with a charge of +1 There are three basic rules for building an atom. First, the atoms of each type of element are defined by the number of they have. Second, excluding hydrogen, the number of is greater than or equal to the number of protons. And third, the number of is the same as the number of protons. B. Write true or false. 1. The smallest particle of matter is an atom. 2. Protons and electrons are roughly the same size. 3. An oxygen atom contains eight electrons. 4. Atoms are not electrically charged. 130 Week 1 EMC 5016 Evan-Moor Corp.

Da Name 3 i l y S c i e nc e All atoms, no matter which element they are, have the same basic structure.

All of an atom s protons and neutrons reside in the nucleus.

contains. OR-bih-tul Electrons occupy the space outside the nucleus a region around the electron and constantly spin around it.

Electrons, however, do not actually orbit the nucleus in a fixed, neutron circular path. Instead, they may move anywhere within their orbital.

For example, calcium has nucleus 20 electrons that are distributed among 10 orbitals. nitrogen atom A. Answer the questions. 1. What does an atom mostly contain?

3 Da Name 3 i l y S c i e nc e All atoms, no matter which element they are, have the same basic structure. An atom consists almost entirely of empty space. Most of the mass that does exist is concentrated in the nucleus, or central core, of an atom. All of an atom s protons and neutrons reside in the nucleus. Since a proton carries a positive charge and a neutron carries no charge, the charge of an atom s nucleus is equal orbital to the number of protons it contains. OR-bih-tul Electrons occupy the space outside the nucleus a region around the electron and constantly spin around it. The areas in which nucleus of an atom that may contain up the electrons spin are called orbitals, or to two electrons electron clouds. Electrons, however, do not actually orbit the nucleus in a fixed, neutron circular path. Instead, they may move anywhere within their orbital. proton An orbital may contain a maximum of two electrons. This means that an atom will have half as many orbitals as it orbitals has electrons. For example, calcium has nucleus 20 electrons that are distributed among 10 orbitals. nitrogen atom A. Answer the questions. 1. What does an atom mostly contain? 2. Where is most of the mass of an atom located? 3. How many electrons can an orbital hold? B. Check the box next to the phrase that completes the analogy. Proton is to nucleus as neutron is to orbital nucleus is to orbital Evan-Moor Corp. EMC indb 131. electron is to orbital atom is to element Week /24/11 9:18 AM

4 Da Name 4 Although they carry no charge, neutrons play an important role in the structure of an atom. Because all protons are positively charged, and because like charges repel each other, protons want to get as far away from each other as possible. But neutrons act like buffers between the protons and hold the nucleus together. The number of protons in an atom is fixed. But the number of neutrons can vary slightly, as long as there are at least as many neutrons as there are protons. Atoms of the same element that contain different numbers of neutrons are called isotopes. For example, a carbon atom, which has six protons, may have six, seven, or eight neutrons. Each of these forms is an isotope of carbon. helium atom lithium atom e hydrogen atom i l y S c i e nc isotopes EYE-suh-tohps two or more forms of an atom that contain different numbers of neutrons carbon atom A. For each atom shown above, count the numbers of protons, neutrons, and electrons. Write the numbers in the columns below. Protons Neutrons Electrons 1. hydrogen 2. helium 3. lithium 4. carbon B. A hydrogen atom doesn t have any neutrons, so why do you think its nucleus does not come apart? indb 132 Week 1 EMC 5016 Evan-Moor Corp. 8/24/11 9:18 AM

5 5 A. Use the words in the box to complete the paragraph. electrons elements isotopes atoms neutrons orbitals protons Matter is made up of particles of these are called, and the smallest. In turn, the particles are made up of positively charged, neutral, and negatively charged. Protons and neutrons are located in the nucleus, while electrons are found in the. Atoms that contain the same number of protons but different numbers of neutrons are called. B. Label the parts of the atom, using the words electron, neutron, nucleus, orbitals, and proton. C. Write the names of four elements Evan-Moor Corp. EMC 5016 Week 1 133

Matter and Atoms. The Structure of Atoms

Matter and Atoms. The Structure of Atoms CHAPTER 11 Matter and Atoms LESSON 2 The Structure of Atoms What do you think? Read the three statements below and decide whether you agree or disagree with them. Place an A in the Before column if you