Bio ch 2

A hydrogen ion, formed during the dissociation of water, has a charge of.

+1 Atoms become ions when they lose or gain electrons. The hydrogen atom has 1 electron. When water releases a hydrogen ion, it is always a hydrogen atom that has lost an electron (the electron stays with the oxygen, producing OH

What are the reasons that the molecule formed by two hydrogen atoms (H2) is stable.

1. It is held together by a covalent bond 2.It has no net charge. 3.It has no unpaired electrons.

Arrange the states of water in order from most dense to least dense (start with most dense at the top).

1. Liquid 2. Solid 3. Gas

An atom has 11 protons, 12 neutrons, and 10 electrons. This atom has an atomic number of ______, an atomic mass of ______, and an overall charge of ______.

11; 23; +1 Atomic mass is equal the sum of protons and neutrons of an atom.

An electrically neutral atom has an atomic number of 11 and an atomic mass of 23. This atom has _______ protons, _________neutrons, and ________electrons.

11;12,11

In a single covalent bond _____ number of electrons are shared.

2 electrons are shared.

If an atom has 4 electrons in its outermost energy level, how many covalent bonds must it form in order to have a stable outer shell of electrons?

4 covalent bonds to be stable

In a double covalent bond, total electrons are shared.

4 shared electrons

Molecules that are more polar tend to have which of the following characteristics?

A higher specific heat, as well as a higher heat of vaporization.

A_________ is a substance or a mixture of substances that act to resist changes in pH.

Buffer

A sodium atom that has lost an electron and has an overall positive charge is an example of which of the following?

Cation

Because polar water molecules attract each other, water is said to be.

Cohesive

In structural formulas, each solid line between atomic symbols represents a single bond.

Covalent bond

Water consists of one oxygen atom joined to two hydrogen atoms by what type of bonds?

Covalent bond

True, discrete molecules form when atoms are connected by

Covalent bonds

What type of bond is formed when 2 atoms share one or more pairs of valence electrons?

Covalent bonds

The affinity of an atom for an electron is also known as

Electronegativity

Atoms are composed of a central nucleus which is surrounded by which orbiting particles?

Electrons

The number and configuration of ______ determines the chemical behavior of an atom.

Electrons

When electrons move closer to the nucleus.

Energy is released

In living systems, what is the catalyze almost every chemical reaction necessary for life?

Enzymes

True or false: Electrons are found in the atom's nucleus.

False

What is the temperature of a substance a measure of?

How fast the molecules are moving

What is an example of a molecular formula

Htiny2, Otiny 2 tiny/substrate.

What atoms usually have no neutrons.

Hydrogen atoms

What type of atoms always have one proton.

Hydrogen atoms

Water consists of one oxygen atom joined to two hydrogen atoms by two single, polar _______ bonds.

Hydrogen bond

Substances that attract water are called _________("water-loving") while substances that repel water are called ________ ("water-fearing").

Hydrophylic, and Hydrophobic

Where are valence electrons found?

In the outermost energy level

The atoms in NaCl are held together by what type of bond?

Ionic bond

Atoms, in which the number of electrons does not equal the number of protons, are called

Ions

When an acid is dissolved in water, how does it change the solution's pH?

It decreases the solution's pH by releasing protons in the solution.

Solid water is _____ dense than liquid water

Less

A dalton is a unit of what?

Mass

Anything that has mass and occupies space is defined as

Matter

A(n) ___________ is made of two or more atoms held together by chemical bonds in a stable association. The atoms may or may not belong to the same element.

Molecule

Isotopes differ in the number of _________they contain.

Neutrons

Almost all the mass of an atom is located in what

Nucleus

What are examples of structural formulas.

O=O, H-H

Substances or a mixture of substances known as buffers, act in living things to resist changes in

PH

How is the crystal structure of salt formed?

Positively charged sodium ions are attracted to negatively charged chloride ions.

Among subatomic particles, each ________ has a charge of +1, each __________ has a charge of -1, and each_________ has no charge.

Proton, Electron, and Neutron

Atomic number refers to the number of what subatomic particle

Protons

Atoms of the same element have the same number of ________ in the nucleus and this number is unique to that element.

Protons

Water consists of one oxygen atom joined to two hydrogen atoms by two single, polar bonds.

Protons and Neutrons

Atoms of different chemical elements can be differentiated based on the number of

Protons in the nucleus

Which two particles are the primary determinants of an element's atomic mass?

Protons, Neutrons

The three main types of subatomic particles are,________ , _______ and _____

Protons, Neutrons, and Electrons

Which subatomic particles are located in the nucleus of an atom

Protons, and Neutrons

When 1 g of sugar is dissolved in 500 mL of water, the sugar is called the _______ and water is called the________

Solute, Solvent

Atoms are composed of what

Subatomic particles

Which of the following is the definition of the heat of vaporization of water?

The amount of energy needed to change 1 g of water from a liquid to a gas

Why is an atom electrically neutral?

There are an equal number of protons and electrons in the atom

Water is cohesive. What describes this feature of water molecules?

They are attracted to each other.

If two atoms belong to the same element, what must be true.

They must have the same number of protons.

Atoms are composed of a central __________which is surrounded by orbiting________

nucleus, electrons

A substance that increases [H+] and decreases pH when it dissociates in water is called a(n)

Acid

The attraction of water to other polar substances is called

Adhesion

What do we call a substance that cannot be broken down into simpler substances by ordinary chemical means?

An element

Atoms with a net negative charge are known as ________ , whereas atoms with a net positive charge are known as_________ .

Anion, Cation