elements and atoms Flashcards
Matter
occupies space and has mass
Element
substances that cannot be broken down or transformed chemically into other substances
Atom
smallest component of an element that retains all of the properties of that element
All atoms contain…
protons, neutrons and electrons
Proton
positively charged particle that resides in the nucleus
The charge of a proton is…
+1
The mass of both protons and neutrons is…
1 amu
Neutron
particle with no charge that resides in the nucleus
Electron
negatively charged particle that travels around the nucleus
The charge of an electron is…
-1
A higher energy level means that…
the electron is further away from the nucleus
AMU is
Atomic Mass Unit
Protons and electrons ___ each other out
balance
Molecules
2 or more atoms that form a chemical bond
Molecules form when…
atoms share electrons to gain a full octet
Is water a compound or molecule?
Both
Compound
at least 2 different types of atoms form a chemical bond
Atomic mass/mass number
number of protons and neutrons (written in top left)
Atomic number
number of protons
Atomic number explains…
the reactions of atoms when combined
Different elements have…
different melting points and boiling points
Isotopes
same element with same number of protons, but different number of neutrons
Radioactive
nucleus decays over time, making atom unstable
Octet rule
atoms want to have full valence electron shells, usually 8 (depending on last energy level)
Chemical bond
attractive forces that hold atoms together, which consists of ionic and covalent bonds
Ionic bonds
electrons are taken and given between atoms
Covalent bonds
electrons are shared between atoms
Both ionic and covalent bonds are…
intramolecular
Polar
one atom of a molecule is positive, while the other is negative (cause by electrons spending more time with one than the other)
Non-polar
both atoms of a molecule are the same charge (electrons spend equal amounts of time with each)
Ion
atom that loses or gains electrons
Cation
loses electrons (positive charge), usually metals
Anion
gains electrons (negative charge), usually nonmetals
Hydrogen bond
attraction between polar molecules where hydrogen is bonded to oxygen, flourine or nitrogen
Hydrophobic interactions
tendency of nonpolar molecules in a polar solvent to interact
Polarity
seperation of charge on opposite sides of a molecule
Cohesion
attraction between positive atom in a polar molecule and a negative atom above the molecule (causes them to stick and form “drops”, ex. H2O)
Surface Tension
cohesion between adjacent molescules that causes the liquid to stick to the side of the solid it is placed in; also causes tightness of water (meaning that organisms can stick on it)
Surfactant
substances that reduce surface tension by increasing the spreading/wetness of water
Hydrophilic
attracted to water, typically soluble in it; occurs at the head of a surfactant
Hydrophobic
insoluble in water; occurs at the tail of a surfactant, where fatty material is present
Properties of water are…
attraction to polar molecules, high specific heat (high energy to raise temperature), high heat of vaporization, lower density of ice than water and high polarity
Water is called the “universal solvent” because…
it dissolves the more substances than any other liquid
