Chem 163 Exam 2 2023 with complete solution questions and answers

law of constant composition pure compound always contains the same percent by mass of each element in the compound atomic theory each element is composed of atoms, which cannot be created or destroyed atoms combine in what ratios whole numbers electron charge negative proton charge positive neutron charge neutral electron atomic mass 0 proton atomic mass 1 amu neutron atomic mass 1 amu where are protons and neutrons? in the nucleus where are electrons? outside the nucleus what does it mean when an atom is neutral It has the same number of protons and electrons where is most of the mass in an atom nucleus where is most of the volume in an atom? outside the nucleus atomic number number of protons in the atom - always a whole number elements are defined by number of protons Z equals number of protons/atomic number ions charged atoms mass number a whole number representing the mass of an atom in amu A equals mass number How is mass number found? protons + neutrons - if you are looking at just the periodic table the atomic mass is rounded to the nearest whole number for mass number subatomic particles with mass protons and neutrons do all atoms of the same element have the same mass? no what is the most common mass for an element? the atomic mass given on the periodic table isotopes Atoms of the same element with the same number of protons but different numbers of neutrons Law of Mendeleev (or the periodic table) when the elements are arranged in order of increasing atomic number (Z), those with similar chemical properties occur at regular periodic intervals rows on the periodic table are called periods - row 1 is period 1 columns on the periodic table are called? groups or families elements in the same group have similar chemical and physical properties Group 1A alkali metals Group 2A alkaline earth metals Group 7A Halogens Group 8A noble gases How are groups named? (other than 1,2,7,8 A) the first element in the group - group 4A is the carbon group what are the A groups on the periodic table called? representative elements (the main/most common elements) what are B groups on the periodic table called? transition elements How can the periodic table be separated? - metals - non-metals - metalloids Periodic table metals left side periodic table non-metals right side periodic table metalloids on zig-zag line on table - aluminum is the exception (it is a metal) what are metalloids elements that have some properties like metals and some like nonmetals Heat capactiy the amount of heat (J) that must be added to a substance to raise its temperature by 1 degree C specific heat capacity the amount of heat energy required to raise the temperature of one gram of substance by 1 degree C P + N = Mass Number How can an atom become charged? Changing number of electrons (because they are on the outside of the atom) Charge of an ion when an atom loses electrons positive charge of an ion when an atom gains electrons negative cation A positively charged ion anion A negatively charged ion Elements in the same group and their ion charge elements in the same group have the same charge as ions Group 1A ion charge +1 Group 2A ion charge +2 Group 3A ion charge +3 Group 4A ion charge +/- 4 Group 5A ion charge -3 Group 6A ion charge -2 Group 7A ion charge -1 Group 8A ion charge 0 light properties waves and particles wavelength distance between crests of a wave wavelength symbol λ (lambda) shorter wavelength colors violet and blue longer wavelength colors red and orange wavelengths (short to long) Gamma ray, x ray, ultraviolet, visable, infared, microwave,and radiowave Between what waves is visible light? ultraviolet and infrared what kind of relationship do wavelengths and energy have? inverse - shorter waves have more energy - longer waves have less energy Quantization of energy electrons can have only certain discrete amounts of energy Bohr theory of atomic structure electron orbits (shells) around the nucleus - the electrons are arranged in energy levels (n) around the nucleus How to know the maximum electrons each electron shell can hold 2n^2 - n is the energy level How many electrons can the first shell hold? 2 electrons How many electrons can the second shell hold? 8 electrons How many electrons can the third shell hold? 18 How many electrons can the fourth shell hold? 32 Valence shell outermost electron shell Valence electrons Electrons on the outermost energy level - the electrons lost, gained, or shared to make chemical compounds Why are chemical properties of the elements on the periodic table periodic? as successive shells of electrons get filled, the valence shell repeats - chemical periodicity occurs every 8 elements What does it mean when an electron moves from a lower to higher energy level? energy is added to the system What does it mean when an electron moves from a higher to lower energy level? energy must be released from the system excited state when an atom absorbs energy, its electrons move to a higher energy level - but eventually electrons have to return to the ground state the energy released for an electron to return to its ground state has to be equal to what? the energy absorbed to reach the higher state How to know the number of possible sublevels contained in an energy level? there are the same amount of sublevels as the number, n (n1 has 1 sublevel, n2 has 2 sublevels) what are the sublevels? s, p, d, f (Some Poor Darn Fool) n1 sublevels s n2 sublevels s and p n3 sublevels s, p, d n4 sublevels s, p, d, f how many subdivisions does the s sublevel have? 1 how many subdivisions does the p sublevel have? 3 how many subdivisions does the d sublevel have? 5 how many subdivisions does the f sublevel have? 7 How many electrons can each subdivision of a sublevel hold? 2 (sublevel f has 7 subdivisions, so as a sublevel, it can hold 14 electrons) Sublevels from lowest to highest energy s p d f where are sublevels? orbitals orbital sizes the size of an orbital depends on which energy level it is inside (an orbital in the third energy level would be bigger than orbital in the second energy level) s orbitals only has one - just a circle p orbitals 3 orbitals - figure 8/infinity sign shape (same shape at three angles) d orbitals 5 orbitals - looks like a four leaf clover what happens to energy as you move down the periodic table? energy increases periodic table sublevels what is sublevel 3d higher/lower than 4s 3d 4p how many valence electrons do all transition elements have? 2 in electron configuration how do you know what electrons are valence? all the electrons connected to the highest energy levels core electrons The electrons in the inner shells of an atom; these electrons are not involved in forming bonds. Atomic size trends on the periodic table - gets bigger down a group - decreases as you move right (down) a period how tightly atoms hold onto valence electrons trends on a periodic table opposite to atomic size trends - held less tight as you move down a group - held tighter moving right in a period ionization energy energy needed to move an electron from a neutral atom to make the atom an ion atom size and ionization energy the smaller the atom, the higher the ionization energy - electrons are held tighter Elements metallic-ness trends on the periodic table - increase as you move down a group - decrease as you go right in a period Periodic table trends in reactivity atoms get more reactive as you go down a group and left in a period - larger atoms are more reactive - moving right in a period loses reactivity what increases as you move left and down the periodic table - atom size - metallicness - reactivity What decreases as you move right and up the periodic table - tightness in which valence electrons are held - ionization energy (needs more energy to remove electrons) what holds atoms together in a chemical bond? - attractive forces - interaction of valence electrons octet rule rule of 8 - atoms lose, gain, or share valence electrons to achieve 8 electrons in the outermost energy level (or 2 for helium) - become isoelectronic with the nearer noble gas isoelectronic same number of electrons How can atoms become isoelectronic and follow the octet rule - transfer valence electrons - sharing valence electrons transfer of valence electrons usually occurs between metal and nonmetal transfer of valence electrons - one atom gives valence electron - one atom takes valence electron - energy is released what happens when an atom gives up a valence electron? - gets smaller - becomes a cation what happens when an atom takes a valence electrons? - gets larger - becomes an anion How does sharing valence electrons work? - usually between two nonmetals - each atom gives at least one valence electron - energy is released - atoms are held together by positive nuclei attraction for electrons of the opposite atoms what happens to energy when atoms share electrons? energy is released what happens to energy when atoms transfer electrons? energy is released Coulomb's law the force of attraction and repulsion between two particles - affected by distance and charge Ionic bond attractive forces between oppositely charged ions (one positive and one negative) - metal and non-metal elements Ionic bond arrangement ions arranged in a crystal lattice - positive and negative ions alternate Chemical reactions occur in order for atoms to finish with. . . 8 electrons in the valence shell molecule 2+ atoms bound together elements the same atom - in a molecule, all the atoms are the same compounds 2 or more elements (kinds of atoms) in a molecule covalent bond A chemical bond formed when two atoms share electrons - shared pair - formed by the electrons of one atom being attracted to the positive nucleus of the other atom - between 2 non-metals what happens to energy when a covalent bond is formed? energy is released How can a covalent bond be shown? H:H H..H H--H In an ionic bond, which element transfers the electron? Metal In an ionic compound, the bond is formed as a result of what? electrostatic (+ and -) attraction In a covalent compound, the bond is a result of what? the shared electrons being attracted by the nucleus of each atom in all chemical compounds, which element comes first? the more metallic element electron pair Pair of electrons with opposite spin in the same orbital unpaired electron a single electron in an orbital the number of what is the number of bonds that can be made in a compound number of unpaired electrons bonding pair a pair of electrons shared between two atoms nonbonding (lone) pairs a pair of electrons from the same atom (not involved in bonding) what bonds are stronger? multiple bonds - double and then triple bonds are the strongest what bonds are the longest? shortest? single bond is the longest triple bond is the shortest electronegativity (EN) the ability for an atom to attract a shared pair of electrons towards itself in a covalent bond - atoms that hold electrons more tightly are more electronegative electronegativity trends on the periodic table increases as you move up and right