Chapter 2 Flashcards
Matter
Anything that takes up space and has mass. Matter is made up from atoms
Element
A pure substance made up of only one kind of atom
Molecule
2 or more atoms bonded together
Compound
A substance consisting of two or more different elements combined in a fixed ratio. Table salt for example is Na(sodium) and Cl(chloride)
Essential elements
A chemical element required for an organism to grow, survive and reproduce. 25of the 92 natural elements are essential for humans. Plants need 17
What makes up 96% of living matter? And the other 4%?
Oxegyn, hydrogen, carbon, nitrogen
Calcium phosphorus, potassium, sulfur and a few others
Trace elements
Elements required by an organism but only in minute quantities.
Atom
The smallest functional units of matter.. Make up all chemical substances and ultimately all organisms
Subatomic particles
The smaller parts that make up an atom. Neutrons protons and electrons are examples
Protons
Electrically and positively charged. Packed tightly with electrons into the atomic nucleus at the center of an atom
Electron
Electrically and negatively charged. Also in the atomic nucleus with the protons. Electrons move rapidly forming a cloud of electric charge around the nucleus. It is the attracting of opposite charged that keeps the electrons in the vicinity of the nucleus.
Neutron
Electrically neutral
Dalton
The unit of measurement for atomic mass equal to roughly the mass of s proton. named after John dalton the British scientist who helped developed atomic theory around 1800.
Atomic mass
It is approximately the equivalent of the usual number of protons and neutrons. Allowing for differences with isotopes
Atomic number
The number of protons an atom has in their nuclei. It is written as a subscript to the left of an elements abbreviation. Unless other wise indicated, an atom is neutral in electrical charge so if it has 2 protons then it has 2 electrons also. Atomic number tells us he number of protons and electrons an electrically neutral atom has
Simplest atom
Hydrogen. Helium is #2
Atomic nucleus
Small dense region consisting of protons and neutrons which gives the atomic nucleus a slight positive charge
Electron speed
An electron could orbit the earth in less than 20 seconds
Orbital
Area where an electron can be found. First one is s shape, second layer is one s and 3 p orbitals
Energy
The capacity to do work to cause change
Lowest energy electrons go
In the first she’ll
Valence electrons
Electrons in the outermost she’ll
Net electric charge of zero
With the exception of ions, the number of protons and electrons is equal which results in a net electric charge of zero
Rows in periodic table
Known as periods, go up and down. They indicate the number of electron shells with the least being at the top
Columns in periodic table
Aka groups read left to right and indicate the number of electrons in the outer shell
Weight vs mass
Weight is the gravitational pull on mass. It is different on earth or the moon but mass is always the same
Mole
Amount of a substance that has as many atoms/molecules/ions/ electrons or photons as atoms in 12 grams of carbon.
Isotope
An element that has a different amount of neutrons than it usually would
Radioisotope
Unstable; how long now they last is measured in half lives ( the time it takes for 50% of the isotope to decay) they emit radiation which in turn makes them more stable
2 ways radioisotopes are used for good
H
Water makes up
60% of humans, 95% of plants
Carbon is* nitrogen is*
A major building block for all living matter,* a vital element in all proteins
Mineral elements essential for life
Calcium, chlorine, magnesium, potassium, phosphorus, sodium, sulfur
Key regulators of water and electric current
Potassium and sodium