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In chemistry, the atom is the basic unit of matter. Structurally, it is composed of a centrally located nucleus within a cloud of negatively charged electrons.

Atoms can be classified based on numbers of electrons, neutrons and protons. The combined number of protons and neutrons is also known as its mass number. The number of protons an atom possesses is also known as it atomic number, which helps identify different elements. The number of neutrons an atom possesses in its nucleus will determine which isotope it is within that element. The number of electrons an atom has within the electron cloud surrounding the nucleus determines whether the atom has a charge or not. If it does have a charge, it is no longer considered an atom but rather an ion. Ions can be positively charged which are known as cations, or negatively charged which are known as anions. 

For example, the element carbon has 6 protons within its nucleus. No other element has 6 protons, and so we can identify the element carbon by its atomic number of 6. A neutrally charged carbon atom also has 6 electrons, where each positive charge in the nucleus is balanced by the negative charge of the electrons, rendering it electrically neutral. Furthermore, a carbon atom typically has 6 neutrons, giving it a mass number of 12. However, there are different isotopes with 8 neutrons present within the carbon atom. This gives it a mass number of 14. Thus, understanding the atom and the terminology associated with it is crucial to understanding molecular composition and quantum chemistry.

Structure of an Atom

1. What is the average atomic mass of zinc according to the following data? Use four decimal places in your answer, do not include units. isotope name isotope mass percentage Zinc-63 63.23456 27.66% Zinc-65 65.03252 remainder 2. How many protons are in an element of 193Pt? 3. A marble is 1.8 cm in diameter. How

Structure of a Atom

Question 1 The diameter of a neutral helium atom is about 168 pm. Suppose we could lin up helium atoms side by side in contact with one another. Approximately how many atoms would it take to make the distance 1 cm from end to end. Round to the nearest whole number, do not include units or commas. do not use scientific notation

Hydrogen Sulfide Elements

Hydrogen sulfide is composed of two elements: hydrogen and sulfur. In an experiment, 6.500 g of hydrogen sulfide is fully decomposed into its elements. A) if 0.384g of hydrogen is obtained in this experiment, how many grams of sulfur must be obtained B) What fundamental law does this experiment demonstrate? C) How is this l

Atomic structure & behavior: A few questions

Explain, phenomena in terms of atomic structure and behavior. 1 When you lightly bump into a car, why does it dent and not create a hole? 2 How does glue or tape stick to things? 3 What happens when a puddle evaporates? 4 What happens when you get a cut or scrape? 5 Why doesn't your hand go through a door when you knock?

Atomic Theory and Bonding Problem Set

1. Draw the lewis structure and indicate the direction of the bond dipole for C-F and Si-S. 2. Draw the lewis structure for NI3 and PF3. 3. Use the symbol for the previous noble gas to indicate core electrons. Write the electron configuration for Z=107. 4. Based on its position on the periodic table, how many 4d electro

Atomic theory and bonding - Lewis structures and ionization energy

1. Predict how valence electrons would pair up in the AsO4-3 ion. 2. Predict the bond angles in SbCl3 and BH3. 3. Predict the geometric structure of the carbonate ion. What bond angles would you predict. Why? 4. Predict the less polar bond in the following pair: Br-Cl or Br-I 5. Using electronegativity, predict in th

Atomic Theory and Bonding

1. On the basis of electronegativity, list the following in order of increasing bond polarity: H-F, H-Cl, H-Br, H-I. 2. Draw the lewis structure and indicate the direction of the bond dipole for C-F and Si-S. 3. Which of the following species is smaller: I or I-? why? 4. What simple ion is formed from the element with Z

Atomic Theory/Nomenclature

Questions: 1) A reaction of one liter of chlorine gas with 3 liters of fluorine gas yields 2 liters of a gaseous product. All gas volumes are at the same temperature and pressure. What is the formula of the gaseous product? 2) Hydrazine, ammonia, and hydrogen azide all contain only nitrogen and hydrogen. The mass of hydr

Atoms and Ions

Select the atom or ion in each pair that has the larger radius. a) Cs or Rb b) Br or As What is the maximum number of electrons that can be identified with each of the following sets of quantum numbers? In some cases, the answer may be "none." In such cases, explain why "none" is the correct answer. a) n=3 b) n=3

Working with pressure and Dalton's Atomic Theory.

Hydrogen gas is contained in a one-liter vessel at "STP"(0 degrees Celsius and 1 Std. Atm.). Flourine gas is contained in a second one-liter vessel at the same conditions of temperature and pressure. Then the two gases are forced into the same one-liter vessel, find: 1) The pressure in this vessel before reaction occurs (ba