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Protons
positively charged, located in the nucleus, number of protons = atomic number
Neutrons
no electric charge, located in the nucleus, slightly bigger than protons, contribute to atomic mass, variations in neutron number create isotopes
Electrons
negatively charged, orbit around the nucleus, much smaller than protons and neutrons, essential for chemical reactions between elements
Shells
different energy levels (closet to the nucleus has the lowest energy), electron capacity increases with shell number (2*n² electrons)
Valence Shell
outermost shell, atoms strive for stability by having full shells (8 electrons in the outermost shell aka octet rule), atoms with incomplete outer shells are more reactive and likely to form bonds
Electron Orbitals
electrons occupy space called orbitals rather than fixed paths, they represent regions where electrons are most likely found
Subshells
electrons are divided into subshells (s = 2, p = 6, d = 10 , f = 14) with increasing capacity
Ionic Bonding
involves one atom taking an electron from another atom (occurs when there is a high difference in electronegativity between the atoms)
Properties of Ionic Bonds
typically form in a crystal lattice structure, have a high melting temperature, are water soluble
Covalent Bonding
atoms share electrons (occurs when there is a low difference in electronegativity between atoms)
Properties of Covalent Bonds
typically exist as liquid and gases, not conductive, form true molecule structure, have a low melting temperature, not usually water soluble, often odorous
Electronegativity
tendency of an atom to attract electrons, difference tells what type of bond they form
Trends in Electronegativity
increases from left to right across a period, increases from bottom to top in a group, helium has the highest electronegativity, francium has the lowest electronegativity
Mixtures
composed of two or more substances combined together
Homogeneous Mixture
uniform composition throughout the mixture (ex. lemonade, salt water, air)
Heterogenous Mixtures
inconsistent component ratios throughout (not uniformly mixed) (ex. trail mix, salad, sand and pebbles)
Solutions
a type of homogenous mixture, composed of a solute (solid) dissolved in a solvent (liquid), (ex. salt water)
Compounds
molecules consisting of two or more DIFFERENT elements chemically bonded together (H20, CO2, H202)
Molecules
a group of atoms chemically bonded together, can consist of the same or different elements
Physical Changes
affect the appearance or form of a substance without altering its chemical composition, can be used to separate components of a mixture into their individual parts (ex. tearing paper, boiling water)
Chemical Changes
involve altering a substance to form a new substance with a different chemical composition, the original substances undergo a chemical reaction resulting in new products (ex. burning candle, digesting food)
Chromatography
a laboratory technique used to separate mixtures into their individual components
Retention Factor
(distance moved by compound)/(distance moved by solvent)
Filtration
separates an insoluble solid from a liquid using a filter
Evaporation
separates a solute from a solvent by evaporating the liquid
Simple Distillation
separates a liquid from a solution and retains it
Fractional Distillation
separates a mixture of two miscible liquids
Magnetism
separating mixtures with one part having magnetic properties
Separating Funnel
immiscible liquids can be separated using their density (this process uses a funnel-like device)
Centrifuging
fast spinning machine that can separate solids from liquids
Crystallization
separating solids by making them crystallize
Sedimentation
separating solids from liquid by letting them settle
Precipitation
creating a solid from a solution
Sieving
uses a sieve to separate mixtures based on particle size
Decantation
separates liquids or homogeneous mixtures by allowing one part to settle and pouring off the liquid
Leaching
extracts a solid by dissolving it in a liquid
Winnowing
uses wind to separate lighter solids from heavier ones
Dilution
involves adding a solvent to a solution without adding more solute, reducing the concentration of the solute (equation: C1*V1 = C2*V2)
Ammonia
a colorless gas with the chemical formula NH3, commonly found in households as a cleaner where it dissolves in water
Dangers of Ammonia
mixing with bleach: produces toxic fumes (such as chloramine gases), can cause severe respiratory damage chemical burns headaches nausea and vomiting
Hydrogen Peroxide
a colorless liquid commonly used as a disinfectant for surfaces and wounds, household concentrations are typically around 3% (found in brown bottles)
Safety and Ingestion Risks
low concentrations (3%): ingestions of small amounts usually cause minor symptoms like stomach irritation, ingestions of larger quantities can lead to more severe irritation and potential chemical burns
high concentrations: ingesting high concentrations can cause severe symptoms, including burns, internal injury, and in some cases, death
Poison Ivy
grows in most regions of the U.S, often in woods, fields, and along roadsides, especially where vegetation is disturbed, identified by three thin, pointy, and shiny leaves
Leaf Color of Poison Ivy by Season
spring: reddish, summer: green, fall: orange to bronze
Allergic Reaction of Poison Ivy
caused by contact with urushiol, an oily mixture with allergenic properties found in poison ivy, contact can occur by touching the plant directly or indirectly via contaminated objects or pets, symptoms: itching, redness, swelling, and blisters (not contagious)
Urushiol
found in poison ivy, mango trees, lacquer trees, poison oak, and other plants in the anacardiaceae family, named after the japanese word “urushi,” meaning lacquer, a pale yellow liquid with a boiling point of 200 C, can be removed with soap and water if the skin has not absorbed it yet
Ricinus
a fast-growing plant, perennial flowering plant native to tropical regions of Africa and widely cultivated around the world, it has large, palmate (hand-shaped) leaves that can vary in color from green to reddish-purple, the plant produces distinctive spiky seed pods that contain castor seeds, which are the sources of castor oil
Toxicity of Ricinus
the seeds of ricinus communis plant contain ricin, a highly toxic protein, ricin can be fatal if ingested, inhaled, or injected, even in small amounts, symptoms of ricin poisoning include nausea, vomiting, diarrhea, and abdominal pain, which can progress to severe dehydration, decreased blood pressure, and organ failure
Uses of Ricinus
despite toxic seeds, castor oil derived from the plant has many uses, including as a laxative, in cosmetics, and as a lubricant
Arsenic
a naturally occurring metalloid found in Earth’s crust, it can exist in several forms: gray (metallic), yellow, and black, with the metallic form being the most common
Arsenic Properties
arsenic is highly toxic and can exist in both organic and inorganic forms, inorganic arsenic compounds, such as arsenic trioxide, are more toxic and are often found in groundwater in certain regions due to natural mineral deposits
Arsenic Uses
historically used in pesticides, herbicides, insecticides, and as a wood preservative, in small amounts, it has been used as medicine, though its toxic effects limit its use
Arsenic Toxicity and Health Risks
arsenic poisoning can occur from inhalation, ingestion, or skin contact with arsenic compounds, symptoms of acute arsenic poisoning include nausea, vomiting, abdominal pain, and diarrhea. chronic exposure can lead to skin changes, cancer, and damage to the nervous system, cardiovascular disease, and diabetes
Mercury Poisoning
typically occurs due to consuming mercury-contaminated fish, exposure from dental fillings, or occupational exposure
Sources of Mercury
fish: particularly tuna, which has high mercury concentrations, dental fillings: amalgam fillings may contain mercury, occupational exposure: jobs involving mercury handling (ex. mining, industrial settings)
Symptoms of Mercury Poisoning
very dependent on the exposure amount, duration, and type of mercury, typical symptoms: weakness, numbness, poor coordination, anxiety, rashes, skin discoloration, poor vision, poor hearing, kidney problems
Risk Groups of Mercury
young children and nursing mothers should monitor fish consumption due to potential mercury exposure
Mercury Onset and Progression
symptoms can take weeks to months to appear, once symptoms appear, they can escalate rapidly, potentially leading to coma or death