In chemistry, if you want to refer to a certain isotope you must write it as such: AXZ. X represents the chemical symbol of the element, Z represents the atomic number, and A represents the mass number which is the number of protons and neutrons combined. For example if one were to refer to a hydrogen isotope, they would write it as 1H1 (ordinary hydrogen), 2H1 (deuterium-hydrogen isotope with one neutron), or 3H1 (tritium-isotope with two neutrons). Light elements usually have an equal amount of neutrons and protons; heavy elements need more neutrons than protons in order to stick together. Atoms with too many neutrons, or not enough, can exist for a while, but they will be unstable.
Main – group metals usually for one cation (positive ion). In a binary ionic compound the metal (cation) is named first. Then the nonmetal (anion) is named, and the suffix -ide is added. To create the formula, you switch the charges, and that tells you how many of each element you will need. For example: Cation Anion Formula Name of Compound Ba2+ I- Ba2+ I- Barium Ion Iodide Ion BaI2 Barium Iodide Type 2: Binary Ionic Type 2 Binary Ionic compounds consist of a metal and a nonmetal.
5. 5. II. Mass Defect and Nuclear Binding Energy Consider a helium-4 atom: (_______ protons, _________ neutrons, and __________ electrons) Recall: 1 proton = 1.007277 u, 1 neutron = 1.008665 u, and 1 electron = 0.000548 u We would expect the mass of a helium-4 atom to be as follows: 2(1.007277 u) + 2(1.008665) + 2(0.000548) = 4.032980 u However the observed mass of a helium-4 atom is 4.002596 u!!!!!! There is a difference of 0.030384 u between the observed mass and the calculated mass.
The first shell can hold up to 2 electrons, second shell can hold up to 8 electrons, third shell can hold up to 18 electrons and the fourth shell can hold up to 32 electrons. The electron configuration is determined by the number of electrons in the outer valance shell and it is used to describe the orbitals which are occupied by the electrons of the atom. The Bohr model of the quantum atom is considered as the cornerstone of quantum mechanics even though it is fundamentally incorrect for all atoms other than hydrogen because Bohr proposed the idea of quantisation for hydrogen’s electronic structure also he was able to explain the emission spectra of hydrogen as thoroughly as other one-electron system. Bohr used spectral evidence to test his atomic theory and he was able to predict that the energy emitted and absorbed by an electron when it changes orbitals would be equivalent to a certain wavelength of electromagnetic radiation and it is possible for it to be measured. He found evidence of his theory of atomic structure which he studied about the spectra and which he chose a specific one which was the hydrogen
Isotopes Lab By: Darlene Cortez (1st Pd) Background: Atoms of the same element that have different masses are known as isotopes. The difference in mass between isotopes is the result of these atoms having different numbers of neutrons. Key vocabulary: Relative abundance- Relative abundance is a component of biodiversity and refers to how common or rare a species is relative to other species in a defined location or community. Weighted average - An average that takes into account the proportional relevance of each component, rather than treating each component equally. Average Atomic Mass- The mass calculated by summing the masses of an elements isotopes, each multiplied by its natural abundance on earth Mass Number- The total
13. Know definitions for the following terms: valence electrons (pg 26), nucleus (pg 26), atom (pg 26), element (pg 27), ion (pg 29), and chemical bond. (pg 28) 14. What are the basic subatomic particles (protons, neutrons, electrons)? (pg 26) Which of these are found in the nucleus?
The different of the chance will form a strong ionic bond between each other. For the non-metallic elements, they will share their electron valence with oxygen to form a stable octet state. However, the covalent bond was not as strong as ionic bond. Along the period 3, from the left the trend in structure is from the metallic oxides containing giant structures of ions, a giant covalent oxide (silicon dioxide) in the middle and molecular oxides on the right. Besides that, along the period 3 from left to right, there is increasing of acidity and decreasing of basicity, decreasing of metallic character, and decreasing of electronegativity difference.
Chemistry I-1 October 27, 2012 Chemistry 1: Bonding Lab Atoms are the essential ingredients in all types of matter. They depend on other atoms to link through chemical bonds from strong attractive forces that exist between the atoms. Being introduced to this lab allowed me to get a better understanding of what a chemical bond is and the various interactions that occur within atoms. The electrons that are in chemical bonds are valence electrons that occur in an atom’s outermost shell. When the two atoms come together they interact and can also repel, but become attracted to the protons inside the atoms.
DISPERSION FORCE / LONDON FORCE The London dispersion force is the weakest intermolecular force. The London dispersion force is a temporary attractive force that results when the electrons in two adjacent atoms occupy positions that make the atoms form temporary dipoles. This force is sometimes called an induced dipole-induced dipole attraction. London forces are the attractive forces that cause nonpolar substances to condense to liquids and to freeze into solids when the temperature is lowered sufficiently. Because of the constant motion of the electrons, an atom or molecule can develop a temporary (instantaneous) dipole when its electrons are distributed unsymmetrically about the nucleus.
Date: October 21, 2012 Class: Survey of the Sciences Subject: Unit 5. Isotopes and Radiation Radioactivity is the emission of energetic particles or waves from atoms. Natural radiation occurs when unstable nuclei transform to some other nucleus by emitting radiation. As they decay over varying lengths of time (from microseconds to hundreds of thousands of years), they emit energetic particles or waves. An isotope is a form of a chemical element whose atomic nucleus contains a specific number of neutron s, in addition to the number of proton s that uniquely defines the element.