General Chemistry PDF

BRIEF REVIEW OF CHEMISTRY: [Chemistry]- Study of structure, properties, composition, and changes that matter undergoes.\ - Study of matter.\ - Central science.\ \ ANTOINE LAVOISIER - Father of modern chemistry. [Matter] - Physical material of the universe.\ - Anything that occupies space, and has...

BRIEF REVIEW OF CHEMISTRY: [Chemistry]- Study of structure, properties, composition, and changes that matter undergoes.\ - Study of matter.\ - Central science.\ \ ANTOINE LAVOISIER - Father of modern chemistry. [Matter] - Physical material of the universe.\ - Anything that occupies space, and has mass. [Mass] -- Refers to the amount of matter present in the material. (Constant)\ [Weight] -- Mass x pull of gravity. (Pull of gravity on moon 1.622 m/s^2^)\ - Varies on the pull of gravity. (9.8 m/s^2^)\ \ **STATES OF MATTER** STATE SOLID LIQUID GAS -------------------------------------- ---------------- ----------------------- ------------------------ Shape: Definite Indefinite Indefinite Volume: Definite Definite Indefinite Rigidity: Rigid Fluid Fluid Density: High Mid Low Compressibility: Incompressible Nearly Incompressible Highly compressible Intermolecular space: Very small Comparatively Large Very Large Intermolecular forces of attraction: Strong Intermediate Weak Molecular motion: Vibration Gliding Constant Random Motion Kinetic enegery: Low Mid High **\ \*\*FLAME TEST: ADDITIONAL INFORMATION ONLY\*\*** **ELEMENT** **NON-LUMINOUS** **COBALT GLASS** ------------- -------------------------- ------------------ Sodium Persistent golden-yellow Nil Potassium Violet Crimson Lithium Crimson Red Purple Calcium Brick red Light Green Strontium Crimson Purple Barium Yellow Green Blue Green **[ANTOINE-LAURENT de LAVOISIER]** - - **[JOHANN WOLFGANG DOBEREINER]** - - - **[JULIUS LOTHAR MEYER & DMITRI MENDELEEV]** - **[HENRY GWYN JEFFREYS MOSELEY]** - - - - - - - - **SUBATOMIC PARTICLE** **CHARGE** **MASS** ------------------------ -------------- ---------------------- **Protons** **Positive** **1.6726 x 10^-24^** **Neutrons** **Neutral** **1.675 x 10^-24^** **Electrons** **Negative** 1. **[BILLIARD BALL MODEL\ ]- John Dalton\ -** Created the **First Atomic Theory (Dalton Atomic Theory)\ \ [DALTON'S ATOMIC THEORY]:\ A.** Each element is composed of extremely small particles called atom.\ **B.** All atoms of a given element are identical, but the atoms of one element are different from the atoms of all other elements.\ **C.** Atoms of one element cannot be changed into atoms of a different element by chemical reactions, atoms are neither created nor destroyed in chemical reactions.\ **D.** Compounds are formed when atoms of more than 1 element combine, a given compound always has the same relative number and kind of atoms. 2. **[RAISIN-BREAD MODEL / PLUM PUDDING MODEL\ ]**- **JJ Thompson\ -** Discovered **ELECTRONS** via the **[cathode ray tube.]** (Radiation travel of cathode to anode) **[CATHODE RAY TUBE:]** Joseph John Thomson (J.J Thomson) conducted the cathode ray experiment. Cathode ray is a radiation produced by a high voltage applied to the electrodes in the tube. It can be seen by the naked eye because they cause certain materials to fluoresce, or to give off light. Cathode rays are deflected by electric or magnetic fields, and J.J Thomson noticed that the ray travelled from negative to positive electrode. Since the ray is attracted to the positively charged electrode, J.J Thomson concluded that cathode ray is a stream of negatively charged particles that we now call electrons. Joseph John Thomson (J. J. Thomson) is widely recognized as the discoverer of the ELECTRON. From the discovery of electrons, he came up and proposed an atomic model called plum pudding model. Joseph John Thomson proposed that the atom consists of a uniform positive sphere of matter in which the mass is evenly distributed and in which the electrons are embedded like raisins in a pudding or seeds in a watermelon.   3. **[PLANETARY MODEL\ ]**- **Niels Henrik David Bohr\ -** Nobel Prize winner **[\ ]**"When electrons jump from lower to higher energy state, emits specific wavelength of light. If falls in visible region, can be seen by naked eye". (Used in Flame Test) 4. **[QUANTUM MECHANICAL MODEL\ ]**- **Erwin Rudolf Josef Alexander Schrodinger\ -** Tells the possible energy states/level of an electron in a hydrogen atom and the probability of its location in a region. The more acceptable model of an atom was formulated by the Austrian physicist Erwin Schrödinger. The electron cloud model shown in Figure 2 is a cloud of rapidly moving electrons\ occupies most of the volume of the atom. The nucleus occupies a tiny region at the center of the atom and is composed of the protons and neutrons. The nucleus contains virtually all the mass of the atom. **\ ** 1. The plum-pudding model was opposed by Ernest Rutherford and Ernest Marsden, his student. They disproved Thomson's model by conducting gold-foil experiment, shown in Figure 1. Rutherford explained the results by postulating the nuclear model of the atom, in which most of the mass of each gold atom and all of its positive charge reside in a very small, extremely dense region that he called the nucleus. He postulated further that most of the volume of an atom is empty space in which electrons move around the nucleus. The discovery of nucleus results to the discovery of neutron (discovered by James Chadwick) and proton (discovered by Ernest Rutherford). The subatomic particles contains a quantity of charges, but for convenience, the charges of subatomic particles are express as 1+ for proton and 1- for electron, and neutron is neutral.  In an atom, the number of proton is equal to the number of electron. Atoms have no net electric charge. 2. 3. More scientists become interested in the study of subatomic particles. Robert Millikan -discovered the elementary charge of an electron using the oil-drop experiment. And he found that the charge of an electron is --1.602 x 10^-19^ C.  What makes an atom of one element different from an atom of another element? The atoms of each element have a characteristic number of protons. The number of protons in an atom of any particular element is called that element's atomic number. Because an atom has no net electrical charge, the number of electrons it contains must equal the number of protons. The elemental symbol is represented by Figure 3 below. **\ **https://lh7-us.googleusercontent.com/EsnmNhJmdP5FIH6uapZ6v1YvWaZijonVRoIYcSzMfstwbofkKBuMt6\_8CTmgzh2pijbm5ApSKKOnlD-FtndP9kSyfzRZWmzCp4ctcImXP\_BDZ5hl\_-WNT11r4QcyKBYnmVyT5SXjcD9wvWjNia82Mg **\ ** Atoms with identical atomic numbers but different mass numbers (that is, the same number of protons but different numbers of neutrons) are called isotopes of one another. Example of carbon isotopes is shown in Table 1 below. **\ Table 1. SOME ISOTOPES OF CARBON** Most elements occur in nature as mixtures of isotopes. We can determine the average atomic mass of an element, usually called the element's atomic weight, by summing (indicated by the Greek sigma, ∑) over the masses of its isotopes multiplied by their relative abundances: Atomic Weight = ∑ \[(isotope Mass) x (isotope abundance)\] **\ ** **1. Law of Conservation of Mass** In simple terms, this law states that matter can neither be created nor destroyed. In other words, the total mass, that is, the sum of the mass of reacting mixture and the products formed remains constant. Antoine Lavoisier gave this law in the year 1789 based on the data he obtained after carefully studying numerous [combustion](https://byjus.com/chemistry/combustion-types/) reactions.\ \ **2. Law of Definite Proportions (Proust's law)** Joseph Proust, a French chemist stated that the proportion of elements by weight in a given compound will always remain exactly the same. In simple terms, we can say that irrespective of its source, origin or its quantity, the per cent composition of elements by weight in a given compound will always remain the same.\ \ **3. Law of Multiple Proportions** This law states that if two elements combine to form more than one compound, the masses of these elements in the reaction are in the ratio of small whole numbers. This law was given by Dalton in the year 1803.\ \ **4.  Gay Lussac's Law of Gaseous Volumes** In 1808, Gay Lussac gave this law based on his observations. This law states that when gases are produced or combine in a chemical reaction, they do so in a simple ratio by volume given that all the gases are at the same temperature and pressure. This law can be considered as another form of the law of definite proportions. The only difference between these two laws of chemical combination is that [Gay Lussac's Law](https://byjus.com/chemistry/gay-lussacs-law/) is stated with respect to volume while the law of definite proportions is stated with respect to mass. **5. Avogadro's Law (aka** **Avogadro's constant.)\ -** Defined as the number of particles per mole (Molecules, atoms, compounds, etc.) of substance. Avogadro proposed this law in the year 1811. It stated that under the same conditions of temperature and pressure, an equal volume of all the gases contains an equal number of molecules. This implies that 2 litres of hydrogen will have the same number of molecules as 2 litres of oxygen given that both the gases are at the same temperature and pressure. There are three types of chemical bonding: Ionic bonding, covalent bonding, and metallic bonding. In this chapter, we will focus on ionic bonding and covalent bonding. The ionic bond consists of a positively charged metal cation and negatively charged nonmetal anion. The bond possesses electrostatic attraction between the oppositely charged ions forming ionic compounds. Covalent bond is formed due to sharing of electrons between atoms. This bond forms molecular compounds. **\ A.  Lewis Symbol & the Octet Rule** To understand the concept of chemical bonding, it is important to define the Lewis symbol and the octet rule. A Lewis symbol is an elemental symbol with electron dots, representing the number of valence electron around a certain atom. Valence electrons are electrons found in the outermost shell of an atom. Those electrons are involved in the chemical bonding. Since it was located in the outer part of the shell, it can be remove or loss easily, or it can be shared easily. An example of the representation of valence electron is shown in Figure 4 below. Sodium atom has only one valence electron. Valence electron is equal to the atom\'s main group number for neutral atoms. Therefore, sodium is located in Group I, hence its valence electron is one. ** ** Atoms often gain, lose, or share electrons to achieve the same number of electrons as the noble gas closest to them in the periodic table. The noble gases have very stable electron arrangements, as evidenced by their high ionization energies, low affinity for additional electrons, and general lack of chemical reactivity. Because all the noble gases except He have eight valence electrons, many atoms undergoing reactions end up with eight valence electrons. This observation has led to a guideline known as the octet rule: Atoms tend to gain, lose, or share electrons until they are surrounded by eight valence electrons. Other atoms follow the noble gasses. They tend to follow its stability, non-reactiveness, and high ionization energy by losing or gaining electrons. Ionic substances generally result from the interaction of metals on the left side of the periodic table with nonmetals on the right side (excluding the noble gases, group 8A). An example of ionic bond is shown in Figure 5 below.  Sodium has low ionization energy compared to chlorine, thus it tends to lose electron easily. Chlorine has higher electron affinity, making it more susceptible to accept electron. Sodium (a metal) and Chloring (a nonmetal) atom react to form an ionic bond. The arrow indicates that the Sodium atom readily give up its electron to the chlorine atom. There has been an electron transfer from Na atom to Cl atom. Hence, Na atom lost electron, and Cl atom gained electron. Na has low ionization energy, which means electrons are easily removed or Na atom easily give up electrons. While Cl has high electron affinity, which means it attracts electrons or readily gains electrons. Ionic bonding forms a solid array or lattice; hence, ionic bonds possess lattice energy that measures the stability of a compound. Lattice energy is the energy required to separate ionic compounds into its gaseous ions, shown in the equation below. https://lh7-us.googleusercontent.com/O0MNxLIZyzstXx2QqzvhcARTpok-fDumJuHsJkZc8v0HRjCMwjisBqN33oVmZEHgJO0dwRTx5lPauzaR8kuibhBpvwX-xFCfvPJ90yDiaVpiTtsdrw\_UjSUzuII\_j4A8vPlUs9sJtCIBFbKLHSkNsQ There is a trend to identify lattice energy using a periodic table. The lattice energy increases from left to right across the period, and increases from bottom to top in a group. This trend is shown in Figure 6 below. Figure 6. Lattice energy trend in a Periodic Table.\  The vast majority of chemical substances do not have the characteristics of ionic materials. Most of the substances with which we come into daily contact---such as water---tend to be gases, liquids, or solids with low melting points. Many, such as gasoline, vaporize readily. Many are pliable in their solid forms---for example, plastic bags and wax. For the very large class of substances that do not behave like ionic substances, we need a different model to describe the bonding between atoms. G. N. Lewis reasoned that atoms might acquire a noble-gas electron configuration by sharing electrons with other atoms. A chemical bond formed by sharing a pair of electrons is a covalent bond. The more common convention is to show each shared electron pair or bonding pair, as a line and any unshared electron pairs (also called lone pairs or nonbonding pairs) as dots.  A covalent may contain a single bond, a double bond, or a triple bond. The bond length of a single bond is greater than a double bond, and the bond length of a double bond is greater than a triple bond. Longer bond length means lower bond strength, and shorter bond length means stronger bond strength. Therefore, a triple bond has the strongest bond strength than a double bond, and a double bond has stronger bond strength than a single bond. **\ ** **\ 1. ELECTRONEGATIVITY\ -** Ability of an element to [ATTRACT] electrons itself.\ **2. ELECTRON AFFINITY\ -** Electron [GAINED] by an atom when an electron is added to it.\ **3. IONIZATION ENERGY\ -** Amount of energy [REQUIRED] to remove an electron from a natural atom. **\ (INCREASING) \ (INCREASING) \\ \ \** - -