ATOMIC NUMBER, MASS NUMBER The atomic number of an element indicates the number

Question

ATOMIC NUMBER, MASS NUMBER The atomic number of an element indicates the number of protons in the nucleus of the atom. The mass number indicates the number of protons and neutrons in the nucleus . The element phosphorus has an atomic number of 15 and a mass number of 31. The phosphorus atom contans electrons. protons, neutrons, and 2. Uranium is the most complicated of the elements that occur naturally A uranium atom has an atomic number of 92 and a mass number of 238. It contains protons, neutrons, and electrons. 3. Isotopes may be defined as atoms that have a) the same atomic number and the same mass number b) different atomic numbers cdifferent mass numbers and the same atomic number ELECTRON ENERGY LEVELS Electrons have potential energy because of their position relative to the (+)nucleus Potential eney s the energy that matter stores because of its position or location. Electrons with lowest potential energy are in energy levels closest to the nucleus. An orbital is the three-dimensional space where an clectron will most likely be found 90% of the time The first energy level has one spherical s orbital (Is orbital) that holds a maximum of two electrons. The second energy level contains one spherical s orbital (2s orbital) and three dumbbell-shaped p orbitals. It holds a maximum of eight electrons. Higher energy levels contain s orbitals, p orbitals, and additional orbitals with more complex shapes Electron configuration refers to the distribution of electrons in an atom's electron shells. Octet rule Rule that a valence shell is complete when it contains eight electrons (except H and He). Valence electrons Electrons in the outermost energy shell. 1. Can the first energy level hold fewer than two electrons? level hold more than two electrons? 2. For the second energy level, the maximum number of electrons is 3. There are 3 electrons in the lithium atom. How many energy levels will the lithium atom have? 4. In the element sodium, atomic number, there are electron configuration for an atom of sodium How many electrons will each energy level of the sodium atom have? Can the first energy electrons Write the IONIZATION 1. Atoms contain equal numbers of protons and electrons Thu, atoms are a) electropositive belectronegative c) clectrically neutral. 2. If an atom loses an electron, it will then have an erl a) negative b) positive c) zero charge

Explanation / Answer

Atomic number and mass number. 1. Phosphorus atomic number is 15. So number of protons will be 15. Number of protons is equal to number of electrons, so it is also 15. And number of neutrons can be calculated as mass number - number of protons as n+p= mass number. So n= 31-15 = 16. P= 15, N= 16 and E=15. 2. Similarly for uranium. Number of protons = number of electrons= atomic number = 92. And number of neutrons will be mass number-no of protons, 238-92= 146. 3. Isotopes is defined as atoms have same atomic number but different mass number. Option c. Electron energy levels. 1. First energy level can accomodate only 2 electrons and not more than that. Though less than 2 it can accommodate like 1 electron as well. 2. For second energy level, 8 electrons can be accomodated at maximum. 3. Lithium will have 2 energy levels, 2 electrons in 1st level and 3rd in the 2nd energy level. 4. Sodium has 11 electrons. It’s configration will be 1s2 2s2 2p6 3s1. So it will have 3 energy level. Ionization 1. Atoms are electrically neutral as number of protons = number of electrons in the nucleus. 2. Positive charge it will have.

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.