Atoms and The Periodic Table Review

The smallest unit of an element that still has the properties of that element is called an atom. Atoms are made up of three subatomic particles: Protons - in the nucleus, positive Neutron – in the nucleus, neutral Electrons – orbit the nucleus, negative Atoms are identified by the number of protons they have, or atomic number.

Protons and neutrons have a mass of one AMU (atomic mass unit). Electrons are much smaller. Their mass is so small, it is not counted in the atom’s total atomic mass. The atomic mass is determined by adding the number of protons and neutrons. The magnetic attraction between the positive protons and the negative electrons keep the electrons in orbit around the neucleus.

Many models of the atom have been made, but the most accepted modern model is The Electron Cloud Model:

An electron shell is a region around the shell in which electrons are found. The first shell can hold 2 electrons, the second can hold 8, and the third can hold 18. The electrons in the outer shell are known as the valence electrons. Atoms that have “full” valence electron shells are stable and less likely to react with other atoms. Other than the first shell, The most stable number of electrons in the valence shell is 8.

When atoms share valence electrons they form a covalent bond. An atom normally has the same number of protons as electrons. Atoms that have more or less electrons that protons are called ions, which have a positive or negative electrical charge. Oppositely-charged ions are attracted to each other and form ionic bonds.

1.Which of the following indicates an atom’s atomic number? A. Number of electron shells in each atom B. Number of protons contained in each atom C. Number of neutrons contained in each D. Number of nuclei contained in each

2. What charge does a proton have? A. Negative B. Neutral C. Atom D. Positive

3.Which of the following is the mass number of an element? A. Number of protons + neutrons B. Number of protons + electrons C. Number of neutrons + electrons D. Number of protons + neutrons + electrons

4.Which model of the atom is currently accepted as the most accurate? A. Bohr Model B. Lewis Model C. Electron Cloud Model D. Einstein Model

5. The atomic mass of number 13, aluminum, is 26. 982 5.The atomic mass of number 13, aluminum, is 26.982. How many neutrons does it have? A. 13 B. 14 C. 15 D. 16

The Periodic Table Elements are made up of only one type of atom. They are organized on The Periodic Table in order of their atomic number. Metals are found to the left of the zig-zag line. Metalloids, which have some of the properties of metals, are found along the zig-zag line. Non-metals are found to the right of the zig-zag line.

Columns in The Periodic Table are called groups Columns in The Periodic Table are called groups. Each member of a group has the same number of valence electron. Rows are called periods. Each element in a period has the same number of electron shells. The groups are: #1: Alkali Metals #2: Alkaline Earth Metals #3-12: Transition Metals

#13: Boron Group #14: Carbon Group #15: Nitrogen Group #16: Oxygen Group #17: Halogens #18: Nobel Gases Group #1 is the most reactive group. It will react easily with group #17. Group #2 will react easily with group # 16.

Metals have certain properties Metals have certain properties. They are malleable (able to be bent, formed, and pounded into thin sheets). Metals can tarnish, which is a chemical reaction with oxygen in which a new substance is formed. Metal are shiny, poor insulators, and good conductors of heat and electricity.

6.Oxygen, chlorine, and sulfur are located on the same side of The Periodic Table because they are all: A. gases B. metals C. metalloids D. nonmetals

7. Element X reacts with K to make K2X 7.Element X reacts with K to make K2X. Which of the following is most likely element X? A. Hydrogen (1 valence electron) B. Nitrogen (5 valence electrons) C. Oxygen (6 valence electrons) D. Fluorine (7 valence electrons)

8.What is happening to the number of protons and neutrons as the mass increases? Atomic # Atomic Mass 1 11 23 21 45 31 70 41 93 The protons are increasing faster than the number of neutrons. B. The protons are decreasing while the neutrons are increasing Neutrons are increasing faster than the protons. Neutrons are decreasing while the protons are increasing.

9.When determining an element’s chemical properties, the MOST important subatomic part to look at is __________. A. protons B. valence electrons C. neutrons D. positrons

10. Which element is a poor conductor of heat? A. F B. K C. Fe D. Ag

KEY B D A C