Chemistry 1 Test Review

For each sub-atomic particle, describe its charge, its contribution to the mass of the atom and where it is found in an atom. In addition, describe the charge of an atom with the same number of protons and electrons. 1) Protons –positive –Has (adds) mass –Found in the nucleus Neutrons –nuetral –Has (adds) mass –Found in the nucleus Electrons –negative –Has virtually no mass –Found in the “electron cloud”

An atom with an equal number of protons and electrons is neutral; the equal number of charges balances out. An atom with an unequal number of protons and electrons is charge. –Negatively charged if it has more electrons –Positively charged if it has more protons 1 – Continued!

ElementSymbol# of Proton s # of Electron s # of Neutron s Atomic Numbe r Atomic Mass Valence Number OxygenO (16) 6 SiliconSi (28) 4 IronFe (56) Variable Aluminum Al (27) 3 Calcium Ca (40) 2 Fill in the following chart: 2)

3) For the element Oxygen: A - 8 P - 8 E - 8 M - 16 A - 8 N - 8 A. How many protons? 8 B. How many neutrons? 8 C. How many electrons? 8 D. Bohr Model p = 8 n = 8

3-continued) For the element Silicon: A - 14 P - 14 E - 14 M - 28 A - 14 N - 14 A. How many protons? 14 B. How many neutrons? 14 C. How many electrons? 14 D. Bohr Model p = 14 n = 14

3-continued) For the element Aluminum: A - 13 P - 13 E - 13 M - 27 A - 13 N - 14 A. How many protons? 13 B. How many neutrons? 14 C. How many electrons? 12 D. Lewis Dot Diagram Al

3-continued) For the element Calcium: A - 20 P - 20 E - 20 M - 40 A - 20 N - 20 A. How many protons? 20 B. How many neutrons? 20 C. How many electrons? 20 D. Lewis Dot Diagram Ca

4) Explain Valence Electrons Valence electrons are the number of electrons on the outter layer (shell, ring, energy level) of an atom. They are a key part of what makes an element behave the way it does. Valence Electrons

4) Cont’d For example, the model of the atom silicon, shown below, has four electrons on the outer ring. It’s Valence Number, therefore, is four (4). Valence Electrons

4) Cont’d Valence electrons follow a pattern on the periodic table. All elements in column one have one valence electron; column two have two. Note that the middle is “variable” (to us in 8 th grade, unknown). 1 2 variable/unknown

5) Where can the protons, electrons and neutrons be found in an atom (be specific)? Protons Neutrons electrons – “energy levels” (orbits) nucleus protons neutrons electrons

6) How do you calculate the mass of an atom? Mass of the atom is the number of protons plus number of neutrons. HINT: it is the “MAN” in APE MAN Mass = number + neutrons (remember that number is protons!)