Ch.2 Section 1-2 Flashcards
Describe the nucleus of an atom.
It is at center of atom and is formed by the strong forces that bind protons and neutrons together.
Which particles are located in the nucleus of an atom? Which is outside?
Inside-protons,neutrons
Outside-electrons
What are the charges of the subatomic particles?
Protons-positive
Electrons-negative
Neutrons-neutral
Why are atoms neutral despite having charged particles?
The atoms have equal amount of neutrons and protons, and because these particles have equal but opposite charges.
What is a chemical element?
A pure substance that consists entirely of one type of atom.
What does an element’s atomic number represent?
The amount protons the element has.
What are isotopes?
Atoms of the same element that differ in the number of neutrons they contain.
How isotopes identified?
By their mass numbers
Why do all isotopes of an element have the same chemical properties?
They have same number of electrons
What is a chemical compound?
A substance formed by the chemical combination of two or more elements in definite proportions.
What does the formula for table salt indicate about a compound?
That the elements from which table salt forms combine in a 1:1 ratio.
What hold atoms in compounds together?
Chemical bonds
What is a covalent bond?
When electrons are shared between atoms
What is a ionic bond?
When one or more electrons are transferred from one atom to another.
What is ion?
Positively and negatively charged atoms
What is the charge of a atom that loses electrons?
Positive
What is molecule?
The structure that results when atoms are joined together by covalent bonds.
What are three facts of covalent bonds?
1) In a water molecule, each hydrogen atom forms a single covalent bond.
2) Atoms can share six electrons and form a triple bond
3) In a covalent bond, atoms share electrons
What are Van dear Waals forces?
The slight attractions that develop between oppositely charged regions of nearby molecules.
What is the charge of a water molecule?
Neutral
What results from the oxygen atom being at one end of water molecule and the hydrogen atoms being at the other end?
The oxygen end of molecule has a slight negative charge and the hydrogen end has a slight positive charge.
Why is a water molecule polar?
Uneven distribution of electrons between the oxygen and hydrogen atoms.
What are facts about hydrogen bonds?
1) The attraction between the hydrogen atom on one water molecule and the oxygen atom on another water molecule is example.
2) They are the strongest bonds that form between molecules.
What is cohesion?
Attraction between molecules of same substance.
What is adhesion?
Attraction between molecules of different substance.
Why is water extremely cohesive?
Because of hydrogen bonding
What is capillary action?
The rise of water in a narrow tube against the force of gravity.
How does capillary action affect plants?
It’s one forces and that draws water out of the roots of plants and up into the stems and leaves.
What is a mixture?
Material composed of two or more elements or compounds that are physically mixed together but not chemically combined.
What is solution?
A mixture of two or more substances in which the molecules of the substances are evenly mixed.
What is greatest solvent in the worlds?
Water
What is a suspension?
Mixtures in nondissolved material
What is solute?
Substance that is dissolved(salt)
What is solvent?
Substance in which solute dissolves(water)
What forms when two water molecules react?
Ions
Why water neutral despite the production of hydrogen ions and hydroxide ions?
Number of positive hydrogen ions is equal to the number of negative hydroxide ions produced.
What does the pH scale indicate?
The concentration of H+ ions on solution
What are the increasingly acidic numbers on a pH scale? Increasingly basic?
Acidic:0-6
Basic:8-14
Neutral:7
How many more H+ ions does a solution with a pH of four have than a solution with pH of five?
Ten times as many
What are facts about acids?
1) Acidic solutions have pH values below 7
2) An acid is any compound that forms H+ ions in solution
3) Acidic solutions contain higher concentration of H+ ions than pure water
What are facts about bases?
1) A base is compound that produces OH- ions in solution
2) Strong bases have pH values ranging from 11 to 14
3) Basic solutions contain lower concentrations of H+ ions than pure water
What are buffers?
Weak acids or bases that react with strong acids or bases to prevent sharp sudden changes in pH.
What is an atom?
Smallest and basic unit of matter
