Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Atoms, matter, pH and water 1 atomic # = # of protons H hydrogen 1.001 Atomic Mass (amu) 1 H hydrogen 1.001 Element Symbol (first letter is always capital and if a second letter exists it is lowercase) Element name (if name doesn’t match the symbol it means the symbol came from its latin name) The elements in Mendeleev’s periodic table are arranged in rows (left to right) called periods. These rows are arranged in order of increasing atomic mass. The elements are also arranged into columns (up and down) called groups or families. The elements within each column have similar chemical properties for example similar boiling points and/or melting points. Elements are any substance that cannot be broken down into simpler substances. A pure substance that consists entirely of one type of atom. Examples: ◦ Hydrogen ◦ Aluminum In comparison a compounds is made up of 2+ different elements. Combined chemically. Examples: ◦ Water (H2O) ◦ Sugar (C6H12O6) Humans are mostly what four elements (96% of your body)? Carbon (C) Hydrogen (H) Oxygen (O) Nitrogen (N) What are the six elements found in every living thing? ◦ Carbon (C) ◦ Hydrogen (H) ◦ Oxygen (O) ◦ Nitrogen (N) ◦ Phosphorus (P) ◦ Sulfur (S) What are the other elements that make up your body called that are found in small amounts like copper and iodine? ◦ Trace Elements! An atom is the smallest particle of an element that has the characteristics of that element and forms the basic building blocks of all matter. In other words, atoms are made up of electrons, protons, and neutrons. Label the atom with the following labels: ◦ Electron ◦ Proton ◦ Neutron Label the atom with the following labels: ◦ Electron ◦ Proton ◦ Neutron Which 2 particles make up the nucleus of an atom? proton and neutron What are the charges on each of the 3 parts of an atom? Electron (e-) -1 Proton (p) +1 Neutron (n) 0 How is an atom held together? ◦Opposite charges attract each other and hold it together. The atomic number tells how many protons an element has. In a NEUTRAL ATOM: number of electrons. Protons equal the There are non-neutral atoms that do not follow this rule! To determine the number of neutrons: Atomic mass = (# of protons) + (# of neutrons) Hint: use algebra to solve for the missing value! Ex: Hydrogen has how many p ________ n___________ and e-____________ Atomic mass = (# of protons) + (# of neutrons) Ex: Hydrogen has how many p 1 n 0 and e- 1 Atomic mass = (# of protons) + (# of neutrons) 1 = (1) +(# of neutrons) # neutrons = 0 Using the periodic table that has been provided to you answer the following three questions: Q: How many protons, neutrons and electrons are in He? p =_____, n = _____, e = _____. Q: How many protons, neutrons, and electrons are in N? p =_____, n= _____, e = _____. Q: How many protons, neutrons, and electrons are in Be? p =_____, n = _____, e = _____. Important: The periodic table is reflecting neutral atoms. We will discuss atoms that are not neutral later (isotopes and ions)! Q: How many protons, neutrons and electrons are in He? p =___2__, n = ___2__, e = __2___. Q: How many protons, neutrons, and electrons are in N? p =__7___, n= ___7__, e = ___7__. Q: How many protons, neutrons, and electrons are in Be? p =__4___, n = ___5__, e = ___4__. A change in the number of protons would change its atomic number, as well as all of its chemical properties. It would be a new element! PROTON COUNT WILL NOT CHANGE! A change in the number of neutrons would NOT change its chemical properties, but will affect the mass. An atom with a different number of neutrons is called an isotope. A change in the number of electrons would change its chemical properties, but it will NOT affect the mass. An atom with a different number of electrons is called an ion. Isotopes occur in nature in very small amounts. In fact, when atomic masses are calculated for the periodic table, the masses of the isotopes are averaged with the common form. Radioactive isotopes have unstable nuclei and can break down at a constant rate over time. The radiation of these isotopes can be dangerous but they are useful in biology. For example, Geologists can determine the age of rocks and fossils. The radiation from some isotopes can be used to detect and treat cancer and some isotopes can be used as “tracers” to tag and follow substances inside of an organism. Electrons float around the nucleus in: Orbitals / Shells / Electron Clouds / Energy Levels How many electrons are in the first orbital (inner shell) of: C (atomic no. = 6) ____ S (atomic no. = 16) ____ N (atomic no. = 7) ____ P (atomic no. = 15 )____ How many electrons are in the first orbital (inner shell) of: Each has 2 electrons 1st orbital holds how many electrons? How many electrons are in the first orbital (inner shell) of: Each has 2 electrons 1st orbital holds how many electrons? 2 How many electrons are in the second orbital of: C (atomic no. = 6) ____ S (atomic no. = 16) ____ N (atomic no. = 7) ____ P (atomic no. = 15 )____ How many electrons are in the second orbital of: C (atomic no. = 6) _4_ S (atomic no. = 16) _8_ N (atomic no. = 7) _5_ P (atomic no. = 15 ) _8_ The Bohr model rules are as follows: 1st orbital : holds at most 2 electrons 2nd and 3rd orbital: holds at most 8 electrons 4th and beyond orbital: holds at most 18 electrons 1) draw a nucleus (write inside the number of protons and neutrons) 2) draw the orbitals filling in the correct number of electrons (until you run out of electrons) Example: Draw the Bohr model of Lithium Example: Draw the Bohr model of hydrogen. Example: Draw the Bohr model of sodium. Why is the Bohr model inaccurate/ outdated? Because electrons don’t exist in perfect orbitals. Scientists believe they exist in clouds. Look at the electron configuration of these first column elements. Explain the trend(s) you see: Look at the electron configuration of these first column elements. Explain the trend(s) you see: They always have 1 electron sitting in their outer shell. What are electrons in the outermost orbital called? Valence Electrons Look at the electron configuration of the second column elements (Be, Mg, Ca), what trend(s) do you see? You may want to try sketching one or two of them out. Look at the electron configuration of the second column elements (Be, Mg, Ca), what trend(s) do you see? You may want to try sketching one or two of them out. They all have 2 electrons in the outermost shell. The numbers above the “A” columns = the number of valence electrons. These are the electrons that react with other elements. 1 2 3 4 5 6 7 8 For now we will ignore the “B” columns (transition metals) because they react differently than the 8 main group elements. How many valence electrons do the following elements have? Mg ____________ O ____________ Cl_____________ How many valence electrons do the following elements have? Mg 2 O 6 Cl 7 Name some atoms that naturally have their outermost shell filled. (He) Helium (Ne) Neon (Ar) Argon (Kr) Krypton These gases are commonly referred to as the noble gases. So what can atoms do to be more like the noble gases / more stable in terms of their electrons? Lose electrons Gain electrons Share electrons Examples: what do the following need to lose (or gain) to be “stable”? Na _________ Be _________ B__________ C__________ N __________ O__________ F_________ Examples: what do the following need to lose (or gain) to be “stable”? Na lose 1 Be lose 2 B lose 3 C lose or gain 4 N gain 3 O gain 2 F gain 1 The process of showing how the atoms bond/ come together is represented in a chemical equations. For example, let’s form 2 water molecules. 2H2 + O2 2H2O What are the substances to the left of the arrow called? REACTANTS What are the substances to the right of the arrow called? PRODUCTS Heterogeneous Mixtures are a combination of substances that when put together the individual components keep their own properties. Give an example of a mixture: ◦ Salad, Trail Mix, Granite Countertop Solutions (aka homogeneous mixtures) are a combination of substances that when put together they are distributed evenly. The substance doing the dissolving is called the solvent and the substance being dissolved is the solute. This is easy to remember because water is often referred to as the universal solvent. Give an example of a solution: Salt Water What part of that is the solute? The solvent? Give an example of a solution: Salt Water What part of that is the solute? The solvent? WATER SALT The pH scale tells the amount of H+ ions in a solution. It is a measure of how acidic or basic/alkaline a solution is. The pH scale ranges from 0 to 14. Substances less than 7 are acidic substances greater than 7 are basic substances at 7 are neutral The true definition of an acid is any substance that forms H+ ions in water. The true definition of a base is any substance that forms OH- ions in water. An example of a neutral solution is: Pure water An example of an acidic solution is: HCl An example of a basic solution is: NaOH Acid + Base = neutralization How does antacid with a pH of 10 soothe an upset stomach? The antacid is basic and when mixed with the acid it causes neutralization A buffer solution is an aqueous solution consisting of a mixture of a weak acid and its conjugate base (or vice versa). The buffer changes very little and is used as a means of keeping pH at a nearly stable value. An example of a buffer solution is water because many life forms only thrive in a relatively small pH range.