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PHYSICAL SCIENCE - Coggle Diagram
PHYSICAL SCIENCE
NUCLEOSYNTHESIS
Nucleosynthesis is the process by which new atomic nuclei are formed from protons and neutrons. This process is responsible for creating the elements found in the universe.
STELLAR
stellar nucleosynthesis occurs in the cores of stars, where nuclear fusion reactions create heavier elements like carbon, oxygen, and iron.
BIGBANG
The first type, called Big Bang nucleosynthesis, happened within the first few minutes after the Big Bang and produced light elements such as hydrogen, helium, and small amounts of lithium.
SUPERNOVA
When massive stars explode in supernovae, even heavier elements such as gold and uranium are formed in a process known as supernova nucleosynthesis.
ATOM
PROTONS
Protons are positively charged particles found in the nucleus of an atom. They determine the atomic number and identity of an element. Protons also contribute to the atom's mass.
ELECTRONS
Electrons are tiny, negatively charged particles that move around the nucleus in energy levels. They are involved in chemical bonding and reactions. In a neutral atom, the number of electrons equals the number of protons.
An atom is the smallest unit of matter. It has a nucleus with protons and neutrons, and electrons that orbit around it. Atoms make up everything around us.
NEUTRONS
Neutrons are neutral particles also located in the nucleus. They have a similar mass to protons and help stabilize the nucleus. Different numbers of neutrons create isotopes of an element.
HYDROGEN BURNING
Hydrogen burning is a nuclear fusion process where hydrogen atoms combine to form helium, releasing a large amount of energy. This reaction powers stars like our Sun and is different from normal burning because it doesn't use oxygen.
The process occurs in the core of stars, where extreme heat and pressure allow hydrogen nuclei (protons) to overcome their repulsion and fuse. This fusion releases energy in the form of light and heat.
During fusion, four hydrogen nuclei turn into one helium nucleus. The small loss of mass is converted into energy, following Einstein’s equation E = mc². This energy is what makes stars shine.
HELIUM BURNING
Helium burning is a stage in a star’s life when helium nuclei fuse to form carbon and oxygen after hydrogen is used up.
This happens at very high temperatures through the triple-alpha process, where three helium atoms combine to create carbon. The energy released supports the star and helps it evolve, producing key elements like carbon and oxygen.
VALENCE ELECTRONS
Valence electrons are the electrons located in the outermost energy level of an atom. They play a key role in determining how an atom interacts with other atoms.
These electrons are involved in chemical bonding, such as forming covalent or ionic bonds. The number of valence electrons influences the atom’s ability to gain, lose, or share electrons.
Atoms with a full outer shell of valence electrons are generally stable and less reactive. In contrast, atoms with incomplete outer shells tend to be more reactive as they seek to fill or empty their valence shell.
ELECTRON CONFIGURATION
Electron configuration shows how electrons are arranged in an atom’s energy levels and orbitals. It tells us which shells and subshells the electrons occupy.
Electrons fill orbitals following certain rules: they go into the lowest energy orbitals first (Aufbau principle), no two electrons have the same quantum state (Pauli exclusion principle), and electrons fill empty orbitals singly before pairing up (Hund’s rule).
Knowing the electron configuration helps us understand an element’s chemical behavior, including how it bonds with other atoms and its reactivity.
COVALENT AND IONIC BONDING
COVALENT BONDING
Covalent bonding happens when two atoms share one or more pairs of electrons to fill their outer shells. This type of bond usually forms between nonmetal atoms and creates molecules with strong connections.
IONIC BONDING
Ionic bonding occurs when one atom donates electrons to another, creating positively and negatively charged ions. These opposite charges attract each other, forming a strong bond, and this usually happens between metals and nonmetals.
Both types of bonding are essential for forming different kinds of compounds. Covalent bonds make up many molecules in living things, while ionic bonds form many salts and crystals.
INTERMOLECULAR FORCES OF ATTRACTION
Intermolecular forces of attraction are weak forces that occur between molecules. They help hold substances together and affect properties like boiling and melting points. Examples include London dispersion forces, dipole-dipole interactions, and hydrogen bonding.
DIPOLE-DIPOLE INTERACTION
These forces occur between molecules that have permanent dipoles—meaning one side is slightly positive and the other is slightly negative. The opposite charges of nearby dipoles attract each other, creating a moderate force of attraction. Dipole-dipole forces are common in polar molecules.
HYDROGEN BONDING
Hydrogen bonding is the strongest type of intermolecular force. It occurs when hydrogen is bonded to a highly electronegative atom like oxygen, nitrogen, or fluorine. The hydrogen atom becomes slightly positive and is strongly attracted to the lone pairs on nearby electronegative atoms, leading to strong interactions between molecules, such as in water.
LONDON DISPERSION FORCES
These are the weakest intermolecular forces and exist between all atoms and molecules. They occur due to temporary shifts in electron density that create brief dipoles, which attract nearby particles. Although weak, they are important in nonpolar molecules and increase in strength with larger or heavier atoms.
POLAR AND NON-POLAR MOLECULES
POLAR MOLECULES
Polar molecules have an uneven distribution of charge, meaning one end is slightly positive and the other is slightly negative. This happens when atoms with different electronegativities share electrons unequally, like in water (H₂O).
NON-POLAR MOLECULES
Nonpolar molecules have an even distribution of charge because the atoms share electrons equally or the molecule is symmetrical. An example is oxygen gas (O₂) or carbon dioxide (CO₂).
The polarity of a molecule affects its physical properties, like solubility and boiling point. Polar molecules mix well with other polar substances, while nonpolar molecules mix with nonpolar substances.
OCTET RULE
The octet rule states that atoms tend to gain, lose, or share electrons to have eight electrons in their outermost shell, making them more stable. This is because having eight valence electrons gives atoms a similar electron arrangement to noble gases, which are very stable.
For example, in water (H₂O), oxygen shares electrons with hydrogen atoms to complete its octet. In sodium chloride (NaCl), sodium gives up one electron to chlorine, allowing both to achieve full outer shells.
The octet rule mainly applies to main group elements, but there are exceptions, especially with elements that can hold more or fewer than eight electrons.
PROPERTIES RESULTING FROM MOLECULAR GEOMETRY
Molecular geometry affects several important properties of molecules, including their polarity, boiling and melting points, solubility, and reactivity.
The shape of a molecule determines how the electrons are distributed and whether the molecule is polar or nonpolar. For example, water has a bent shape, making it polar, while carbon dioxide is linear and nonpolar.
These geometric differences influence how molecules interact with each other, affecting physical properties like how easily a substance evaporates, dissolves, or reacts with other substances.
MOLECULAR GEOMETRY
Molecular geometry is the three-dimensional shape of a molecule, determined by the arrangement of atoms and the electron pairs around the central atom. It depends on the number of bonding and lone electron pairs, following the VSEPR theory (Valence Shell Electron Pair Repulsion).
Common molecular shapes include linear, bent, trigonal planar, tetrahedral, trigonal pyramidal, and octahedral. These shapes help determine the molecule's polarity, reactivity, and physical properties like boiling point and solubility.
For example, a water molecule has a bent shape, making it polar, while carbon dioxide is linear and nonpolar. Understanding molecular geometry is key to predicting how molecules behave.