tailieunhanh - Lecture Biology - Chapter 2: Basic chemistry

After studying this chapter, you should be able to accomplish the following outcomes: Distinguish between matter, elements, and atoms; name the six elements that are basic to life; describe the structure of an atom; tell why an atom can have isotopes; give examples of how low levels and high levels of radiation can each be helpful;. | Basic Chemistry Chapter 2 Atomic Structure All matter is composed of atoms. Understanding the structure of atoms is critical to understanding the nature of biological molecules. Atomic Structure Atoms are composed of -protons – positively charged particles -neutrons – neutral particles -electrons – negatively charged particles Protons and neutrons are located in the nucleus. Electrons are found in orbitals surrounding the nucleus. Atomic Structure Atomic Structure Every different atom has a characteristic number of protons in the nucleus. atomic number = number of protons Atoms with the same atomic number have the same chemical properties and belong to the same element. Atomic Structure Each proton and neutron has a mass of approximately 1 dalton. The sum of protons and neutrons is the atom’s atomic mass. Isotopes – atoms of the same element that have different atomic mass numbers due to different numbers of neutrons. Atomic Structure Atomic Structure Neutral atoms have the same number of protons and electrons. Ions are charged atoms. -cations – have more protons than electrons and are positively charged -anions – have more electrons than protons and are negatively charged Atomic Structure Electrons are located in orbitals surrounding the nucleus. Each orbital can contain only 2 electrons. Electrons possess potential energy, with electrons far from the nucleus having the most energy. Atomic Structure Atomic Structure Electrons can be transferred from one atom to another, while still retaining the energy of their position in the atom. -oxidation = loss of an electron -reduction = gain of an electron Elements Valence electrons are the electrons in the outermost energy level of an atom. An element’s chemical properties depend on interactions between valence electrons of different atoms. Elements The Periodic Table arranges all elements according to their atomic number. The table identifies elements with similar chemical | Basic Chemistry Chapter 2 Atomic Structure All matter is composed of atoms. Understanding the structure of atoms is critical to understanding the nature of biological molecules. Atomic Structure Atoms are composed of -protons – positively charged particles -neutrons – neutral particles -electrons – negatively charged particles Protons and neutrons are located in the nucleus. Electrons are found in orbitals surrounding the nucleus. Atomic Structure Atomic Structure Every different atom has a characteristic number of protons in the nucleus. atomic number = number of protons Atoms with the same atomic number have the same chemical properties and belong to the same element. Atomic Structure Each proton and neutron has a mass of approximately 1 dalton. The sum of protons and neutrons is the atom’s atomic mass. Isotopes – atoms of the same element that have different atomic mass numbers due to different numbers of neutrons. Atomic Structure Atomic Structure .