Elements in the Same Family (Column) on the Periodic Table All Have

The Periodic Tabular array

The periodic table shows all the elements and their physical properties; information technology is bundled based on diminutive numbers and electron configurations.

Learning Objectives

Identify the common periodic trends that can be deduced from the periodic table of elements

Central Takeaways

Key Points

• The periodic tabular array lists all the elements, with information about their atomic weights, chemic symbols, and diminutive numbers.
• The arrangement of the periodic tabular array leads us to visualize certain trends among the atoms.
• The vertical columns (groups) of the periodic tabular array are arranged such that all its elements have the same number of valence electrons. All elements within a certain group thus share similar properties.

Key Terms

• diminutive number: The number, equal to the number of protons in an atom, that determines its chemical properties. Symbol: Z
• group: A vertical column in the periodic table, which signifies the number of valence shell electrons in an element's atom.
• period: A horizontal row in the periodic table, which signifies the total number of electron shells in an element'southward atom.

Element Symbols

The periodic table is structured as an xviii X seven filigree, positioned above a smaller double row of elements. The periodic table only lists chemical elements, and includes each isotope of each element inside one jail 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, then on. About elements are represented by the first letter or showtime two letters of their English name, but there are some exceptions. 2 notable exceptions include silverish and mercury. The symbol for argent is "Ag" from Latin argentum, which means "gray" or "shining." The symbol for mercury is "Hg" from the Latinized Greek hydrargyrum, which ways "water-silver." Many periodic tables include the full name of element likewise and color-code the elements based on their phase at room temperature (solid, liquid, or gas).

The periodic tabular array: The periodic table is a tabular brandish of all the chemical elements. The atoms are grouped in lodge of increasing atomic number.

Rows and Periods

The element symbol is ever about accompanied by other information such as diminutive number and diminutive weight. Atomic number describes the number of protons in 1 atom of that chemical element. For case, an cantlet of oxygen contains 8 protons. Elements are listed in club of increasing atomic number from left to correct. Each row of the periodic table is called a flow and each cavalcade of the periodic table is chosen a group (or family). Some groups have specific names similar the halogens or noble gases. Elements inside the same period or grouping take similar properties.

Determining Chemical Properties using the Periodic Table

Chemical backdrop of each element are adamant by the chemical element's electronic configuration, and peculiarly by its outermost valence electrons. An element's location in the periodic table is largely dependent on its electrons; the number of valence shell electrons determines its grouping, and the type of orbital in which the valence electrons lie in determines the chemical element's cake. In addition, the total number of electron shells an atom determines which catamenia information technology belongs to. Because of its structure, the periodic tabular array has become an extremely useful tool for assessing and predicting elemental and chemic trends.

Chemical science iii.1 Introduction to the Periodic Table – YouTube: An introduction to the periodic table which identifies metals,,nonmetals, and metalloids by location and compares and contrasts the concrete properties of metals and nonmetals.

Molecules

Molecules are electrically neutral compounds made of multiple atoms bound together by chemic bonds.

Learning Objectives

Recognize the full general properties of molecules

Central Takeaways

Key Points

• Molecules are neutral and do non bear whatsoever charge.
• A molecule may consist of nonmetallic atoms of a single chemical element, every bit with oxygen (O₂), or of different elements, as with water (H_iiO).
• The geometry and composition of a molecule volition determine its chemical and physical backdrop.
• Isomers are molecules with the aforementioned atoms in different geometric arrangements.

Primal Terms

• covalent: when 2 or more nonmetallic atoms are jump together by sharing electrons.
• isomer: Molecules with the same number of atoms in different geometric arrangements.
• compound: when 2 or more unlike atoms are held together past a covalent bond. All compounds are molecules but not all molecules are compounds.
• molecule: Two or more atoms that are held together by a chemic covalent bond.

Atoms and Molecules

An cantlet is defined as a bones unit of matter that contains a centralized dense nucleus surrounded by an electron cloud. When 2 or more atoms are held together by a chemical 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 written report. For example, the term "molecules" is used in the kinetic theory of gases, referring to any gaseous particle regardless of its composition.

About oftentimes, the term "molecules" refers to multiple atoms; a molecule may exist composed of a single element, as with oxygen (O₂), or of multiple elements, such every bit water (H_iiO). Molecules are neutral and carry no accuse; this property distinguishes them from polyatomic ions, such as nitrate (NO_three ^–).

caffeine molecule: Caffeine is a complicated molecule, composed of many atoms bonded to each other in a specific system.

Molecular size varies depending on the number of atoms that make upwards the molecule. Most molecules are too minor to exist seen with the naked eye. The smallest molecule is diatomic hydrogen (H_ii), with a bail length of 0.74 angstroms. Macromolecules are large molecules equanimous of smaller subunits; this term from biochemistry refers to nucleic acids, proteins, carbohydrates, and lipids. Some macromolecules may exist observed by specialized microscopes.

Often, a compound 'southward limerick can besides be denoted past an empirical formula, which is the simplest integer ratio of its elective chemical elements. Withal, this empirical formula does non e'er describe the specific molecule in question, since information technology provides only the ratio of its elements. The full elemental composition of a molecule can be precisely represented by its molecular formula, which indicates the exact number of atoms that are in the molecule.

Example

• C₆H₁₂O_vi = molecular formula for glucose
• CH₂O = empirical (simplified ratio) formula for glucose

Isomers

Isomers are molecules with the same atoms in unlike geometric arrangements. Because of these different arrangements, isomers oft have very different chemical and physical properties. In the picture beneath, 1-propanol is mostly used in the synthesis of other compounds and has a less offensive smell, whereas 2-propanol is the common household alcohol.

propanol structural isomers: The chemical formula for propanol (C₃H₇OH) describes several dissimilar molecules, which vary by the position of the alcohol (OH). Each molecule is a structural isomer of the other.

Ions

An ion is an cantlet or molecule that has a net electrical charge because its full number of electrons is non equal to its number of protons.

Learning Objectives

Compare the different classes of ions

Key Takeaways

Key Points

• Ions are formed when the number of protons in an atom does non equal the number of electrons. If more protons are present, the ion is positive and is known as a cation; if more electrons are present, the ion is negative and referred to as an anion.
• Ions are highly reactive species. They are generally found in a gaseous state and do non occur in abundance on Earth. They are repelled past like electric charges and are attracted to opposite 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 because at that place are fewer electrons in the deject to repel each other.

Key Terms

• ion: An atom or group of atoms bearing an electrical charge, such equally the sodium and chlorine atoms in a salt solution.
• anion: Ions that are negatively charged because they have more electrons than protons.
• cation: Ions that are positively charged considering they have more protons than electrons.

An atom is a basic unit of measurement of affair that consists of a dense nucleus composed of positively charged protons and neutral neutrons, which is surrounded by a cloud of negatively charged electrons. If an atom has the same number of protons and electrons, it is electronically neutral. However, if the total number of electrons does not equal the number of protons, the cantlet has a net electric accuse.

Whatsoever atom or molecule with a cyberspace charge, either positive or negative, is known equally an ion. An ion consisting of a unmarried cantlet is a monoatomic ion; an ion consisting of two or more atoms is referred to as a polyatomic ion. The positive electric charge of a proton is equal in magnitude to the negative charge of an electron; therefore, the net electric charge of an ion is equal to its number of protons minus its number of electrons.

Ions are highly reactive species. They are generally establish in a gaseous state and do non occur in affluence on World. Ions in the liquid or solid state are produced when salts interact with their solvents. They are repelled by like electric charges and are attracted to opposite charges.

Types of Ions

There are specialized types of ions. Anions have more electrons than protons then have a net negative accuse. Cations have more protons than electrons and then have a internet positive charge. Zwitterions are neutral and have both positive and negative charges at different locations throughout the molecule. Anions are generally larger than the parent molecule or atom, considering the excess electrons repel each other and add to the physical size of the electron deject. Cations are generally smaller than their parent cantlet or molecule due to the smaller size of their electron clouds.

Hydrogen ions: The human relationship between a molecule, its cation, and its anion is shown.

An ion is denoted past writing its internet negative charge in superscript immediately afterward the chemical structure for the atom/molecule. Conventionally the net accuse is written with the magnitude before the sign; the magnitude of singly charged molecules/atoms is more often than not omitted. Monoatomic ions are sometimes also represented by Roman numerals, which designate the formal oxidation state of the element, whereas the superscripted numerals announce the internet charge. For example, Fe²⁺ can exist referred to as Fe(Two). These representations can exist thought of as equivalent for monoatomic ions, just the Roman numerals cannot be applied to polyatomic ions.

Forming Ions

Ions tin be 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 vanquish of an atom; the inner-shell electrons are more tightly leap to the positively charged nucleus and and so practice non participate in this type of chemical interaction.

Ionization generally involves a transfer of electrons between atoms or molecules. The process is motivated by the achievement of more stable electronic configurations, such every bit the octet rule, which states that virtually stable atoms and ions accept eight electrons in their outermost (valence) vanquish. Polyatomic and molecular ions tin also exist formed, more often than not by gaining or losing elemental ions, such as H⁺, in neutral molecules. Polyatomic ions are generally very unstable and reactive.

An mutual case of an ion is Na⁺. Sodium has a +one charge because sodium has eleven electrons. However, co-ordinate to the octet rule, sodium would be more stable with 10 electrons (2 in its inner most shell, 8 in its outermost vanquish). Therefore, sodium tends to lose an electron to become more stable. On the other hand, chlorine tends to gain an electron to become Cl^–. Chlorine naturally has 17 electrons just information technology would be more stable with 18 electrons (ii in its inner most crush, 8 in its second shell, and viii in its valence shell). Therefore, chlorine will take an electron from another cantlet to get negatively charged.

Periodic Properties: Part 3, Ionic Radius, Predicting Ionic Charges – YouTube: A continuation of the discussion of periodic properties, including ionic radius and how to predict ionic charges.

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