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bio chapter 2
biology exam 1
| Question | Answer |
|---|---|
| What is an atom? | Smallest unit of matter that still retains the properties of an element, composed of subatomic particles |
| What is an element? | A substance that cannot be broken down to other substances by chemical reactions EX: iron, sodium, and oxygen |
| What is a compound? | A substance consisting of two or more elements in a fixed ratio, has different characteristics from those of its elements like H2O and NaCl |
| What is matter? | anything that has mass and takes up space. All organisms are composed of it, and it is composed of elements. |
| What are the four elements that make up 96% of living organisms? | oxygen (O), Carbon (C), Hydrogen (H), and nitrogen (N) |
| What organisms make up 3.7% of living organisms? | Calcium, phosphorus, potassium, sulfur, sodium, chlorine, magnesium |
| What is a trace element? | elements are required by organisms but only in one-minute quantities |
| What is a neutron? | no electric charge, mass of 1 Dalton |
| What is a proton? | a positive electric charge [+], mass of 1 Dalton |
| What is an electron? | a negative electric charge [-], mass of 1/2000th of a Dalton |
| What forms the atomic nucleus? | Neutrons and protons |
| What forms a cloud that orbits around the nucleus? | Electrons |
| What is an atomic number? | number of protons in atomic nucleus |
| What is mass number? | Sum of mass of number of protons and neutrons in atomic nucleus |
| What is atomic mass? | An atom's total mass, can be approximated by the mass number |
| If the atomic number was 11 and the mass number is 23, then how many neutrons are there? | 12 neutrons |
| What are isotopes? | Two atoms of element that differ in number of neutrons. EX: carbon-12 (12^/6 C) |
| What are radioisotopes? | unstable and decay spontaneously, giving off particles and energy. Both carbon -12 + -13 are stable, but -14 is unstable |
| How are radioisotopes used today? | Dating fossils, tracing atoms through metabolic processes, diagnosing medical disorders |
| What is an electron shell? | An electron's state of potential energy |
| How are electron shells and energy levels related? | The energy level depends on the layer of the shell. EX: first shell is the lowest energy level, second shell is the higher energy level, third shell is the highest energy level |
| What is the valence shell? | The outermost shell |
| How do the valence shells become full? | Atoms without full valence shells participate in chemical reactions to fill the valence shells. Valence shells with fewer atoms go to valence shells with almost full valence shells |
| What is an electron orbital? | A region where an electron can hang out around an atom |
| What is a chemical bond? | They hold atoms together in molecules, ions, and other structures |
| What are the four chemical bonds? | Covalent bonds, ionic bonds, hydrogen bonds, Van der Waals interactions |
| What are cations? | Positive charged ions |
| What are anions? | Negative charged ions |
| What is an ionic bond? | attraction between negative charged anion and the positive charged cation |
| What is the difference between a compound and a molecule? | A compound is a substance formed by the chemical bonding of more than one type of element in a fixed proportion and a molecule is a group of two or atoms joined together by chemical bonds |
| What are polar bonds? | Covalent bonds in which the electrons forming the bond are unequally distributed |
| What are nonpolar bonds? | No charge selection, covalent bond in which the electrons are shared equally between the atoms |
| What are chemical reactions? | making and breaking of chemical bonds |
| What are reactants and substrates? | Starting molecule of a chemical reaction |
| What are products? | Final molecule of a chemical reaction |
| What is chemical equilibrium? | When the forward and reverse reaction rates are equal (no net changes in concentration) |
| What is the reversibility of a chemical reaction? | a chemical reaction in which the conversion of reactants to products and converting products to reactants co-occur. |
Created by:
josie_d
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