Elements of the Same Family Would Also Have the Same Number of
The Periodic Tabular array
The periodic table shows all the elements and their physical properties; it is arranged based on diminutive numbers and electron configurations.
Learning Objectives
Place the mutual periodic trends that can be deduced from the periodic tabular array of elements
Key Takeaways
Key Points
- The periodic table lists all the elements, with information about their atomic weights, chemical symbols, and diminutive numbers.
- The organization of the periodic table leads u.s.a. to visualize certain trends among the atoms.
- The vertical columns (groups) of the periodic table are arranged such that all its elements take the aforementioned number of valence electrons. All elements within a certain group thus share similar properties.
Key Terms
- atomic number: The number, equal to the number of protons in an atom, that determines its chemical properties. Symbol: Z
- grouping: A vertical column in the periodic table, which signifies the number of valence crush electrons in an element's atom.
- menstruation: A horizontal row in the periodic tabular array, which signifies the total number of electron shells in an element's atom.
Element Symbols
The periodic table is structured equally an xviii X 7 grid, positioned to a higher place a smaller double row of elements. The periodic tabular array only lists chemical elements, and includes each isotope of each element inside one cell. In the typical periodic table, each chemical element is listed by its element symbol and atomic number. For example, "H" denotes hydrogen, "Li" denotes lithium, and and so on. Most elements are represented by the commencement letter or offset two messages of their English language name, but there are some exceptions. Two notable exceptions include silverish and mercury. The symbol for silver is "Ag" from Latin argentum, which means "gray" or "shining." The symbol for mercury is "Hg" from the Latinized Greek hydrargyrum, which means "water-silver." Many periodic tables include the full name of chemical element also and color-code the elements based on their phase at room temperature (solid, liquid, or gas).
The periodic table: The periodic table is a tabular display of all the chemical elements. The atoms are grouped in order of increasing atomic number.
Rows and Periods
The element symbol is always nearly accompanied by other information such as atomic number and atomic weight. Atomic number describes the number of protons in ane cantlet of that chemical element. For example, an atom of oxygen contains 8 protons. Elements are listed in order of increasing atomic number from left to correct. Each row of the periodic table is chosen a period and each column of the periodic tabular array is called a grouping (or family). Some groups have specific names similar the halogens or noble gases. Elements within the same catamenia or grouping have similar properties.
Determining Chemic Properties using the Periodic Tabular array
Chemical properties of each element are adamant past the element'southward electronic configuration, and specially past its outermost valence electrons. An element's location in the periodic tabular array is largely dependent on its electrons; the number of valence trounce electrons determines its group, and the blazon of orbital in which the valence electrons lie in determines the chemical element's block. In addition, the total number of electron shells an atom determines which menstruation information technology belongs to. Considering of its construction, the periodic tabular array has go an extremely useful tool for assessing and predicting elemental and chemic trends.
Molecules
Molecules are electrically neutral compounds made of multiple atoms bound together by chemic bonds.
Learning Objectives
Recognize the general properties of molecules
Key Takeaways
Key Points
- Molecules are neutral and do not carry any accuse.
- A molecule may consist of nonmetallic atoms of a unmarried chemical element, as with oxygen (O2), or of different elements, equally with water (HiiO).
- The geometry and composition of a molecule will decide its chemical and concrete properties.
- Isomers are molecules with the same atoms in different geometric arrangements.
Key Terms
- covalent: when ii or more nonmetallic atoms are bound together by sharing electrons.
- isomer: Molecules with the same number of atoms in different geometric arrangements.
- chemical compound: when two or more different atoms are held together by a covalent bond. All compounds are molecules simply not all molecules are compounds.
- molecule: Two or more atoms that are held together by a chemical covalent bond.
Atoms and Molecules
An atom is defined equally a bones unit of matter that contains a centralized dense nucleus surrounded by an electron cloud. When two or more than atoms are held together by a chemic covalent bond, this new entity is known as a molecule. The word "molecule" is a loose term, and it colloquially carries different meanings across different fields of study. For instance, the term "molecules" is used in the kinetic theory of gases, referring to any gaseous particle regardless of its composition.
Most often, the term "molecules" refers to multiple atoms; a molecule may be composed of a single chemical element, as with oxygen (Oii), or of multiple elements, such as water (H2O). Molecules are neutral and carry no charge; this property distinguishes them from polyatomic ions, such as nitrate (NO3 –).
caffeine molecule: Caffeine is a complicated molecule, equanimous of many atoms bonded to each other in a specific arrangement.
Molecular size varies depending on the number of atoms that make upwardly the molecule. Well-nigh molecules are too pocket-sized to be seen with the naked eye. The smallest molecule is diatomic hydrogen (Hii), with a bail length of 0.74 angstroms. Macromolecules are large molecules composed of smaller subunits; this term from biochemistry refers to nucleic acids, proteins, carbohydrates, and lipids. Some macromolecules may be observed by specialized microscopes.
Often, a chemical compound 's composition can also exist denoted past an empirical formula, which is the simplest integer ratio of its constituent chemical elements. However, this empirical formula does not always describe the specific molecule in question, since it provides only the ratio of its elements. The full elemental limerick of a molecule can exist precisely represented past its molecular formula, which indicates the verbal number of atoms that are in the molecule.
Instance
- CviH12Ovi = molecular formula for glucose
- CHtwoO = empirical (simplified ratio) formula for glucose
Isomers
Isomers are molecules with the aforementioned atoms in different geometric arrangements. Because of these dissimilar arrangements, isomers often have very unlike chemical and concrete properties. In the movie below, 1-propanol is generally used in the synthesis of other compounds and has a less offensive olfactory property, whereas 2-propanol is the common household alcohol.
propanol structural isomers: The chemical formula for propanol (CthreeHviiOH) describes several different molecules, which vary past the position of the alcohol (OH). Each molecule is a structural isomer of the other.
Ions
An ion is an atom or molecule that has a net electrical charge because its total number of electrons is non equal to its number of protons.
Learning Objectives
Compare the unlike classes of ions
Key Takeaways
Fundamental Points
- Ions are formed when the number of protons in an atom does not equal the number of electrons. If more protons are present, the ion is positive and is known every bit a cation; if more electrons are present, the ion is negative and referred to every bit an anion.
- Ions are highly reactive species. They are more often than not found in a gaseous state and do non occur in affluence on Earth. They are repelled by like electric charges and are attracted to reverse charges.
- The electron cloud of an atom determines the size of the atom; added electrons (anions) increase the electron repulsion, increasing the ion's size, while cations (with less electrons) are smaller than the atom considering there are fewer electrons in the cloud to repel each other.
Fundamental Terms
- ion: An cantlet or group of atoms bearing an electrical accuse, such as the sodium and chlorine atoms in a common salt solution.
- anion: Ions that are negatively charged because they take more electrons than protons.
- cation: Ions that are positively charged because they have more protons than electrons.
An atom is a bones unit of measurement of matter that consists of a dumbo nucleus composed of positively charged protons and neutral neutrons, which is surrounded past a deject of negatively charged electrons. If an cantlet has the same number of protons and electrons, information technology is electronically neutral. However, if the total number of electrons does not equal the number of protons, the atom has a net electric charge.
Any atom or molecule with a net charge, either positive or negative, is known equally an ion. An ion consisting of a single cantlet is a monoatomic ion; an ion consisting of two or more than atoms is referred to equally a polyatomic ion. The positive electric charge of a proton is equal in magnitude to the negative charge of an electron; therefore, the net electrical charge of an ion is equal to its number of protons minus its number of electrons.
Ions are highly reactive species. They are generally plant in a gaseous country and exercise not occur in affluence on Globe. Ions in the liquid or solid state are produced when salts interact with their solvents. They are repelled by like electrical charges and are attracted to contrary charges.
Types of Ions
At that place are specialized types of ions. Anions have more electrons than protons and so have a net negative charge. Cations have more protons than electrons and and then take a net positive accuse. Zwitterions are neutral and have both positive and negative charges at different locations throughout the molecule. Anions are more often than not larger than the parent molecule or atom, because the excess electrons repel each other and add to the physical size of the electron cloud. Cations are generally smaller than their parent atom or molecule due to the smaller size of their electron clouds.
Hydrogen ions: The human relationship betwixt a molecule, its cation, and its anion is shown.
An ion is denoted by writing its net negative accuse in superscript immediately after the chemical structure for the cantlet/molecule. Conventionally the cyberspace charge is written with the magnitude earlier the sign; the magnitude of singly charged molecules/atoms is by and large omitted. Monoatomic ions are sometimes also represented by Roman numerals, which designate the formal oxidation state of the chemical element, whereas the superscripted numerals denote the net charge. For instance, Atomic number 26ii+ can be referred to as Fe(II). These representations can be thought of as equivalent for monoatomic ions, but the Roman numerals cannot be practical to polyatomic ions.
Forming Ions
Ions tin exist formed by ionization, which is the process of a neutral atom losing or gaining electrons. Generally, the electrons are either added to or lost from the valence shell of an atom; the inner-shell electrons are more tightly bound to the positively charged nucleus and then do non participate in this type of chemical interaction.
Ionization generally involves a transfer of electrons between atoms or molecules. The process is motivated past the achievement of more stable electronic configurations, such as the octet rule, which states that about stable atoms and ions have eight electrons in their outermost (valence) shell. Polyatomic and molecular ions tin can also exist formed, more often than not past gaining or losing elemental ions, such as H+, in neutral molecules. Polyatomic ions are generally very unstable and reactive.
An mutual instance of an ion is Na+. Sodium has a +one charge because sodium has 11 electrons. However, according to the octet dominion, sodium would be more stable with 10 electrons (ii in its inner most beat out, eight in its outermost shell). Therefore, sodium tends to lose an electron to get more stable. On the other hand, chlorine tends to gain an electron to become Cl–. Chlorine naturally has 17 electrons but it would be more stable with 18 electrons (2 in its inner most shell, viii in its second shell, and 8 in its valence shell). Therefore, chlorine volition take an electron from another atom to get negatively charged.
Source: https://courses.lumenlearning.com/boundless-chemistry/chapter/the-periodic-table/
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